Gratins

Ingredients

Equipment Needed

• •Four shallow 5- to 6-inch (13 to 15 cm) broiler-safe gratin dishes
• •Rimmed baking sheet
• •Medium saucepan
• •Balloon whisk
• •Mandoline or sharp chef's knife

Instructions

1. 1

   Set the four forms

   Heat the oven to 375°F (190°C) with a rack in the upper third. Butter four shallow 5- to 6-inch (13 to 15 cm) broiler-safe gratin dishes with 1 tablespoon (15 ml / 14 g) of the butter and place them on a rimmed baking sheet. Mark one dish for each form. Reserve one-quarter of the sliced potatoes, about 8 oz (225 g), raw for the gratin complet; the remaining potatoes will be cooked before receiving the faster finishes.

2. 2

   Build the cream sauce

   Reserve 2 tablespoons (30 ml / 31 g) of the milk for adjusting the sauce. Melt 2 tablespoons (30 ml / 28 g) butter in a saucepan over medium-low heat, stir in the flour, and cook for 2 minutes without letting the roux colour. Whisk in the remaining milk gradually, then add the cream, 1 teaspoon (5 ml / 6 g) salt, the white pepper, and nutmeg. Simmer gently for 5 minutes, whisking, until the sauce is smooth and nappé, meaning it coats the back of a spoon. If lumps form, take the pan off the heat and whisk firmly; strain it if necessary. Ça se rattrape. If it becomes too thick to flow, loosen it with the reserved milk. Cover and keep warm.

3. 3

   Bake the gratin complet

   Arrange the reserved raw potatoes in overlapping layers in the first dish. Pour over 3/4 cup (180 ml) of the warm sauce, pressing gently so it reaches between the slices. Mix 3 tablespoons (45 ml / 11 g) breadcrumbs with 2 teaspoons (10 ml / 9 g) melted butter and scatter them evenly over the surface. Bake for 35 to 45 minutes, until a knife passes through the centre without resistance and the crust is deep bronze. This simultaneous cooking of the raw ingredient and its crust is the gratin complet. If the top colours before the potato softens, cover it loosely with foil and continue; shielding the crust is a rescue, not a shortcut.

4. 4

   Cook the remaining potatoes

   When the gratin complet has about 15 minutes left, bring a wide saucepan of water to a simmer with 2 teaspoons (10 ml / 12 g) of the salt. Add the remaining potatoes and simmer for 7 to 9 minutes, until tender all the way through but still holding their shape. Drain them thoroughly and let their surface moisture evaporate for a minute in the warm pan. Divide them among the three remaining dishes and keep them covered so they stay hot. The rapid, light, and glazed forms depend on this readiness; the broiler colours a surface, it does not cook a cold centre.

5. 5

   Finish the gratin rapide

   Fold 1/2 cup (120 ml) warm sauce through the potatoes in the second dish. Mix 3 tablespoons (45 ml / 11 g) breadcrumbs with 2 teaspoons (10 ml / 9 g) melted butter and spread them over the top. Remove the gratin complet from the oven, cover it loosely, and turn the broiler to high. Set the gratin rapide about 6 inches (15 cm) below the heat for 2 to 4 minutes, rotating once if needed, until the surface bubbles at the rim and takes a mottled bronze crust. If the centre has cooled, stop and warm the dish for 8 minutes at 375°F (190°C), then broil again; prolonged broiling would burn the crumbs before warming the potatoes.

6. 6

   Make the gratin léger

   Spread the hot potatoes in the third dish in a single shallow layer. Mix the remaining 2 tablespoons (30 ml / 8 g) breadcrumbs with 2 teaspoons (10 ml / 9 g) melted butter and scatter this light veil over the top. Broil for 1 to 3 minutes, just until the crumbs turn pale gold and crisp. Gratin léger describes the lighter degree of coating and colour, not an invitation to omit the butter. Watch closely, because a thin covering goes from blond to burnt quickly.

7. 7

   Apply the glaçage

   Put 1/2 cup (120 ml) of the warm sauce in a bowl and let it stand for 2 minutes, then whisk in the egg yolk. The sauce should be warm enough to remain fluid but not so hot that the yolk scrambles. If it tightens or turns grainy, whisk in a spoonful of the reserved cool milk and strain it. Coat the potatoes in the fourth dish with a thin, even layer and use no crumbs. Broil for 30 seconds to 2 minutes, until the glaçage swells slightly and develops smooth golden freckles. This is a form of gratin rapide, distinguished by its enriched glazed surface.

8. 8

   Compare and serve

   Bring the four dishes to the table together. The gratin complet should be tender and deeply set beneath its crust; the gratin rapide should carry the firmest contrast between creamy potato and crisp crumbs; the gratin léger should wear only a delicate buttered veil; and the glaçage should be smooth, golden, and free of crumbs. Spoon a little of each onto every plate while the edges still gleam. Cooking well is not cooking fancy. À table!

Chef Tips

• •A gratin is defined by the crust and the heat that makes it, not by cheese. Gruyère has its proper place in many named gratins, but the four classical forms can be understood through sauce, breadcrumbs, butter, and glaçage alone.
• •Use shallow dishes. A deep casserole asks the broiler to warm several inches of food while it colours a surface, and those two jobs cannot finish together. Broiler-safe ceramic or enameled metal both work.
• •Fine, dry breadcrumbs make an even crust. Fresh coarse crumbs brown in isolated pebbles and leave pale gaps, which is pleasant on some baked dishes but less useful when studying the precise gratin forms.
• •Serve these beside a roast chicken, a veal roast, or simply dressed bitter leaves. A dry white Burgundy has enough freshness for the cream and enough body for the browned butter.

Advance Preparation

• •The sauce can be made one day ahead, covered directly on its surface, and refrigerated. Reheat it over gentle heat with a spoonful of milk, whisking until smooth.
• •The potatoes for the rapid, light, and glazed forms can be cooked earlier in the day. Cool and refrigerate them promptly, then warm them completely in the oven before applying the final top heat.
• •Slice and assemble the gratin complet shortly before baking. Raw sliced potatoes darken as they stand, and holding them in water would wash away the starch that helps bind the sauce.
• •The gratin complet and gratin rapide tolerate gentle reheating at 325°F (165°C). The gratin léger and glaçage are best finished immediately before serving because their delicate surfaces soften as they wait.

Frequently Asked Questions

Nutrition Information

1 serving (about 340g)