The term “gratin” refers to the cooking vessel and the way it is used, not just the dish itself. Anything can be cooked “au gratin” and there are many variations of gratins – just potatoes, or potatoes mixed with other root vegetables, such as parsnip, turnip, or onion.
Mushrooms, kale, artichoke hearts, olives can be included, as well. A gratin can be made with or without cheese, with cream, milk, stock, or any combination of these. In summer, I make gratins with vegetables that are “wet” (tomatoes, eggplant, etc.) and the only liquid I use is a little bit of flavorful olive oil. In colder months I make traditional creamy, cheesy gratins with roots and tubers.
You can be precise in the way you lay in the ingredients or you can be casual. Bear in mind that the thickness of the cuts, the density of the vegetables, and how tightly packed in the dish everything all affect the cooking times. This recipe is a variation of a quiche I used to make, and it is named for my wife Denise, who likes it so much I can never make enough.
8-10 medium/largish potatoes such as Yukon Gold, Yellow Finns or Russets
3 firm apples or pears
2 cups or more grated cheese (use Swiss such as Gruyere or Jarlesberg, or a medium sharp cheddar)
1/2 lb. smoky ham, very thinly sliced (almost shaved) such as Black Forest
2 1/2 to 3 cups liquid such as cream, milk, stock, or a mixture of these
2 tablespoons fresh chopped herbs of your choice, such as thyme, sage and rosemary
2-3 medium brown onions, sliced into 1/2 inch thick half-moons and sautéed until soft
Salt and fresh ground black pepper to taste*
Preheat the oven to 400°F.
Rub a gratin dish (9 x 13 casserole dish) with a peeled and split garlic clove to impart a subtle garlic flavor without getting chunks of burnt garlic. Rub the dish with a little oil or butter. (Rub the entire inside of the dish with oil or butter to facilitate cleaning the dish later.)
Lay the cooked onions into the bottom of the dish and spread evenly over the surface.
Using a knife or mandoline, slice the potatoes into uniform slices anywhere from 1/8 to 1/4 inch.
Peel the apples, then cut in half. Core them and slice them thinly.
Drain the potatoes and layer overlapping slices on the bottom of the dish a couple layers thick. Season with salt and pepper and some of the herbs.
Lay in the sliced apples or pears and moisten the surface with a few spoonfuls of the liquid.
Lay in a couple more layers of spuds, salt and pepper, and then the ham. Again with the liquid and herbs.
A couple more layers of potato, then some cheese, liquid, salt and pepper, and herbs.
Continue with the potatoes until you are 1/2 inch from the top or you are out of potatoes. Add in the rest of the liquid or enough to come just below the top layer. Push down with the palm of your hand to get the top layer wet. Season with salt and pepper and some herbs, and a sprinkling of cheese if you like.
Place the gratin dish on a sheet pan before baking as this dish will invariably bubble over and splatter the oven floor, creating a mess and smelling really bad as it burns.
Bake in the middle of the oven for 45 minutes to 1 hour, until golden brown and the potatoes are tender. If the gratin is done but there is too much liquid, stick a paper towel into the corners to wick off the excess liquid. If the opposite occurs, microwave some stock until hot and drizzle into the corner and continue cooking. Be sure to cook until the surface is golden and crisp in places.
Serve hot or warm. This dish re-heats quite well so can be made ahead. As it is rather rich, a salad is a good accompaniment.
YIELD: 8-10 servings
SOURCE: Chef Andrew Cohen
*Remember that the ham and cheese will contribute to the saltiness of the dish, so go light.