Italian Tuscan Black Kale Gratin | Cavolo Nero Gratinato al Pecorino Toscano
Cavolo nero is the one vegetable in the Tuscan garden that improves after being ignored. It stands upright through autumn looking tough and unappetising, and then the first hard frost arrives and the leaves change. Starch turns to sugar, the bitterness recedes, the blades soften and darken. A plant that tasted coarse in October tastes sweet and deep in December, and nobody in a hurry ever discovers it.
This gratin puts that frost sweetened leaf under a crust rather than into a soup, which is where cavolo nero normally ends up. The leaves are stripped from the rib, blanched, squeezed hard and folded into a light bechamel built with semistagionato Pecorino Toscano DOP, then covered with coarse country breadcrumbs, more pecorino and a little Parmigiano Reggiano.
The whole thing is an argument about salt. Pecorino Romano is salted hard and matured to be grated over pasta in small quantities. Pecorino Toscano at four months is mild, milky and salted with restraint, so it can be used in the volume a gratin needs.
Yield: 6 side dish servings. Prep: 30 minutes. Cook: 45 minutes. Rest: 10 minutes. Total: about 1 hour 25 minutes. Difficulty: intermediate. Course: contorno. Region: Tuscany, the Chianti hills and the Val di Greve.
The Story
The plant is cavolo nero riccio di Toscana, a loose leaved kale that never forms a head, with narrow blistered blades the colour of a wet slate roof. Grown in central Italy since at least the sixteenth century, it belongs to the mezzadria, the sharecropping system that shaped the Tuscan countryside until after the war. A sharecropper handed over half of everything valuable he grew, and what stayed in his kitchen was what the landlord did not want.
Its famous destination is ribollita, the twice cooked bread and bean soup of Florence and the Val di Greve, where cavolo nero, cannellini beans and stale unsalted bread are cooked, rested overnight and reboiled. The rule that governs ribollita governs this gratin too: the kale is not the garnish, it is the structure. The leaves also went into farinata with polenta flour, and were served boiled under new oil during the November olive harvest.
The pecorino comes from the other half of that landscape. Pecorino Toscano DOP is made across the Crete Senesi, the Maremma and the Val di Chiana, largely by Sardinian shepherd families who moved north in the 1950s to take on abandoned farms. It exists in two forms, a soft cheese aged twenty days and a firmer one aged four months or more, and neither is salted the way the Roman cheese is. At four months it melts into a smooth savoury body rather than oily threads.
Ingredients
For the black kale
Cavolo nero, black kale, 2 lb (900 g) untrimmed, about 1 1/4 lb (570 g) of leaf
Coarse sea salt for the blanching water, 2 tbsp (36 g)
Extra virgin olive oil, Tuscan if possible, 3 tbsp (45 ml)
Garlic cloves, thinly sliced, 3
Dried red chilli, small, crumbled, 1
Fine sea salt, 1/2 tsp (3 g)
Freshly ground black pepper, to taste
For the pecorino bechamel
Whole milk, 2 cups (480 ml)
Unsalted butter, 3 tbsp (43 g)
All purpose flour, 1/4 cup (30 g)
Pecorino Toscano DOP semistagionato, aged about 4 months, finely grated, 4 oz (115 g)
Bay leaf, 1
Whole nutmeg, a few scrapes
Fine sea salt, 1/4 tsp (1.5 g), added only after tasting
Freshly ground black pepper, to taste
For the gratin topping
Coarse breadcrumbs from stale saltless Tuscan bread, 1 cup (60 g)
Pecorino Toscano DOP semistagionato, coarsely grated, 1 1/2 oz (43 g)
Parmigiano Reggiano, finely grated, 1 oz (28 g)
Extra virgin olive oil, 2 tbsp (30 ml)
Fresh rosemary leaves, very finely chopped, 1 tsp (1 g)
For finishing
Extra virgin olive oil, new season if available, for the final drizzle
Freshly ground black pepper, to taste
Finely grated lemon zest, from 1/4 lemon, optional
Preparation
Step 1
Strip and wash the leaves. Hold each stalk by the thick end of the rib and pull the leaf away in one movement. The rib is fibrous and never softens in the time the blade needs, so it goes in the compost. Wash the leaves in two changes of cold water, since the blistered surface traps grit along the veins.
Step 2
Blanch and shock. Bring a large pot of water to a rolling boil and salt it heavily, which seasons the leaf and holds the green. Cook the leaves 4 to 5 minutes, until a thick part of a blade gives easily between finger and thumb, then lift them straight into iced water. This stops the cooking dead and fixes the dark colour that would otherwise turn olive grey in the bake.
Step 3
Squeeze the kale properly. Drain the leaves, then take them in handfuls and squeeze hard, harder than feels reasonable. Every millilitre left inside comes out in the oven and thins the bechamel into a puddle. Squeeze each handful twice, then chop the compact balls into pieces of about 1 inch (2.5 cm).
Step 4
Build flavour in the pan. Warm the olive oil over medium low heat with the sliced garlic and crumbled chilli for about 2 minutes without letting them colour, since browned garlic turns bitter and the kale has bitterness of its own. Raise the heat, add the chopped leaves and turn them 3 to 4 minutes until glossy and hot through. Season and set aside.
Step 5
Infuse the milk and make the pecorino bechamel. Bring the milk to just below a simmer with the bay leaf, take it off the heat for 10 minutes, then discard the leaf. Melt the butter over medium low heat, add the flour and cook the roux a full 2 minutes, whisking, until it smells of toasted biscuit. Pour in the warm milk in three additions, whisking each smooth, then simmer 5 minutes until the sauce coats a spoon. Off the heat, wait 1 minute, then whisk in the pecorino in three handfuls. Add nutmeg and pepper, and taste before deciding whether any salt is needed at all.
Step 6
Combine and fill the dish. Fold the kale into the bechamel off the heat until every piece is coated but the sauce is still visibly loose, slightly too wet. Butter a 9 by 13 inch (23 by 33 cm) dish and spread the mixture no deeper than 1 1/2 inches (4 cm), since a deeper layer steams and never sets.
Step 7
Top and bake. Mix the breadcrumbs, both cheeses and the rosemary, then rub in the olive oil with your fingertips until the crumbs are evenly damp. Scatter them over the surface without pressing down. Bake at 400°F (200°C) on a middle shelf for 25 to 30 minutes, until the top is deep gold and the edges bubble. Rest 10 minutes before serving.
Plating
This is a contorno and it is served hot, but not straight from the oven. The ten minute rest is functional: the bechamel is still liquid the moment it comes out and a portion cut immediately slumps across the plate. Ten minutes later the sauce holds a clean edge while staying creamy, and the crust cracks instead of bending.
Serve it in its dish when the table is family style, which is how it is eaten in Tuscany, or cut squares with a thin knife and lift them with an offset spatula. Use warm plates rather than hot, and set the piece down crust side up without ever spooning sauce over it. Anything poured on that crust destroys in a second what the oven took half an hour to build.
Finish each portion with a thread of new season olive oil, the peppery kind pressed in November, and a grind of pepper. A little grated lemon zest is optional and lifts the sheep cheese. This belongs beside roast pork loin, grilled bistecca or a bowl of cannellini beans.
Professional Technique
The defining technique is the management of a cheese that does not want to be melted in quantity. Pecorino has a firmer protein network and a higher fat content than cow milk cheeses of the same age, and heated above roughly 175°F (80°C) in a sauce those proteins tighten and expel their fat. That is the oily stringy mess most pecorino gratins become. The defence is temperature discipline: the bechamel comes off the heat, rests a minute, and takes the cheese in three handfuls, each one dropping the sauce temperature slightly.
The second technique is blanching for colour rather than for softness. Cavolo nero is full of chlorophyll that a long gentle cook degrades into pheophytin, the dull brown green pigment of overcooked greens. A short violent boil in heavily salted water, followed at once by iced water, denatures the enzymes responsible before the pigment can shift. The leaf then spends half an hour under a crust without losing the near black green that gives the dish its name.
The third is the saltless Tuscan bread for the crumbs. Pane toscano is baked without salt, a habit going back to medieval salt taxes, and its dry open crumb breaks into coarse irregular fragments rather than the fine sand a soft loaf gives. Those fragments trap oil unevenly and brown unevenly, which is what produces a broken glassy crust.
Texture and Moisture Control
Water is the enemy here and it arrives from one source, the kale itself. A blanched leaf that has been drained but not squeezed carries close to its own weight in water, and all of it is released in the oven into a sauce that was correctly made. The result is a gratin sitting in a grey pool with a crust floating on top, and no oven temperature compensates for it.
The bechamel is deliberately built looser than it should look, at roughly the consistency of pouring cream. Two things thicken it afterwards: the starch goes on gelatinising in the oven, and the crumb topping draws moisture upward as it toasts. A sauce that looks perfect before baking will be pasty after, so judge it by how it flows off the spoon.
The crust is a matter of fat distribution and depth. Rubbing the oil through the crumbs coats each fragment individually, so the whole surface crisps at the same rate, while oil drizzled on top soaks a few patches and bakes in stripes. Scatter the crumbs loosely, because steam trapped under a compacted layer softens the crust from below.
Professional Mise en Place
Almost everything here is done ahead in a professional kitchen: the kale is blanched and squeezed in the morning, the bechamel is made and held, and only the assembly and the bake happen to order.
Equipment and tools
Large pot for blanching and a bowl of iced water
Wide saute pan for the garlic and kale, heavy saucepan for the bechamel
Balloon whisk, and a fine rasp for the pecorino and the nutmeg
Baking dish 9 by 13 inch (23 by 33 cm), earthenware or enamelled cast iron
Thin bladed knife and an offset spatula
Prepared ahead
Kale blanched, shocked, squeezed and chopped, 2 days ahead, refrigerated
Bechamel made and cooled with film on the surface, 2 days ahead
Breadcrumbs from stale bread, dry in a sealed jar, 1 week ahead
Cheeses grated and kept apart, fine and coarse
Garlic sliced and chilli crumbled on the day, never in advance
Service setup
Oven fully up to 400°F (200°C) with a shelf in the middle position
Bechamel rewarmed and loosened with a splash of milk
Crumb and cheese topping mixed with the oil 30 minutes before baking
Dish assembled and topped only as it goes into the oven
Plates warm rather than hot, and the new oil open at the pass
Chef Tips
Buy cavolo nero after the first cold nights. The frost sweetening is measurable: the plant converts starch into sugars as an antifreeze response, and a leaf picked in December is markedly sweeter than the same leaf in September. Early in the season, blanch a minute longer and add a pinch of sugar to the bechamel.
Taste the pecorino before you weigh it. It varies between producers and between wheels, and a saltier than average one means using none of the extra salt in the bechamel. Grate a little, taste it alone, and adjust. This is the one place the dish can be ruined by obedience.
Save the blanching water. It is heavily salted, deeply green and full of flavour, and in Tuscan kitchens it goes into the next day bean soup. Cool it and refrigerate for two days.
For a feast day version, replace 1/4 cup (60 ml) of the milk with heavy cream and lay finely sliced boiled potato under the kale. It holds better on a long buffet and it is the form this gratin takes at Christmas in plenty of Tuscan households.
Common Mistakes
Using Pecorino Romano instead of Pecorino Toscano. Romano is salted and matured to be a seasoning, not a body, and in the quantity a gratin needs it makes the dish inedibly salty. If you cannot find Toscano, a young Sardinian pecorino is a far closer substitute.
Leaving the central ribs in. The rib needs three times longer than the blade to soften, so it stays stringy through the whole bake and ruins every second forkful. Strip every leaf by hand before washing.
Not squeezing the blanched leaves hard enough. Residual water is released in the oven and turns a correctly made bechamel into a thin grey pool. Squeeze in handfuls until they no longer drip, then squeeze again.
Adding the pecorino to a boiling sauce. Sheep milk cheese heated above about 175°F (80°C) tightens and releases its fat, giving a stringy oily bechamel that never recovers. Take the pan off the heat, wait a minute, and whisk the cheese in through three separate additions.
Pressing the topping down or filling the dish too deep. A compacted crumb layer bakes into a lid and goes soft from underneath, and above 1 1/2 inches (4 cm) the centre steams instead of setting. Use a wider dish, never a deeper one.
Wine Pairing
Vernaccia di San Gimignano DOCG: The historic white of Tuscany and the most precise match here. Its firm acidity cuts the butter and the sheep fat in the bechamel, and the bitter almond note it finishes on runs alongside the residual bitterness of the kale rather than fighting it.
Offida Pecorino DOCG: A Marche white with a coincidence of name and a real affinity of flavour. The Pecorino grape gives high acidity with body behind it, a saline edge and a note of aniseed and yellow flowers that plays against the rosemary in the topping.
Chianti Rufina DOCG: From the coolest and highest of the Chianti zones, northeast of Florence, which gives sharper acidity and a leaner frame than Chianti Classico. That acidity slices through the fat instead of sitting on it, and the sour cherry and dried herb character echoes the garlic and chilli under the kale.
Carmignano DOCG: The small zone west of Florence where Sangiovese has been blended with Cabernet since the eighteenth century. The Cabernet contributes a leafy green note that finds the kale directly, while the tannin stays fine enough not to clash with the cheese. Open it when the gratin sits beside roast pork.
Rosso di Montalcino DOC: Younger and more immediate than its Brunello sibling, with bright red fruit, moderate tannin and a savoury earthy base that suits a baked vegetable far better than an aged wine would. The gentle grip handles the crust without overwhelming a contorno.
Storage & Reheating
The baked gratin keeps refrigerated for up to 3 days, covered tightly once completely cold. Never cover it warm: trapped steam condenses on the film and rains back onto the crust, which turns to paste overnight. Cool it uncovered for an hour, then seal it.
Reheat in the oven and only in the oven. A microwave rehydrates the topping and gives a uniformly damp dish that has lost the one contrast the recipe is built on. Bring the portion to room temperature for 20 minutes, then reheat at 375°F (190°C) for 12 to 15 minutes, uncovered, on the top third of the oven. If the crust softened in the refrigerator, scatter fresh oiled breadcrumbs over it first.
Freeze it before baking, never after. Assemble without the topping, freeze for up to 2 months, thaw overnight, add fresh crumbs and bake as normal with 10 minutes added. A baked and frozen gratin thaws into a watery mess, because ice crystals rupture the kale cells the squeezing emptied.
Nutrition
Per serving, based on 6 side dish portions:
Calories: 315 kcal
Total Fat: 21 g
Saturated Fat: 9 g
Trans Fat: 0.3 g
Unsaturated Fat: 11 g
Cholesterol: 38 mg
Sodium: 520 mg
Total Carbohydrates: 19 g
Fiber: 3.5 g
Total Sugars: 5 g
Added Sugars: 0 g
Protein: 14 g
Lactose: 3.2 g
Principal micronutrients: vitamin K, vitamin A, vitamin C, calcium, folate, manganese, iron
These figures are estimates. Cavolo nero is exceptionally high in vitamin K and in the carotenoids lutein and zeaxanthin, most of which survives blanching. The coarse salt in the blanching water is discarded with it, so the sodium reflects the cheeses.
Comments