Today was our Parish's old-fashioned picnic, and a lot of friends asked for the recipe for the potato gratin that I always bring to it. It's just a classic French gratin of potatoes with cream and Gruyere cheese, kicked up a notch with country ham and sage. It's the perfect dinner party dish, because it's easy, elegant, can be served in its baking dish, and is a real crowd pleaser.
Here's the recipe.
Christ Church Episcopal Potato Gratin, A.K.A. French Potato Gratin with Country Ham and Sage
2 large yellow onions, trimmed, split lengthwise, peeled, and thinly sliced
2 tablespoons unsalted butter
2 pounds russet (baking potatoes, about 4 large)
2 cups (1 pint carton) heavy cream
1 ounce country ham (1 slice) or prosciutto, cut into fine julienne
2 tablespoons chopped fresh sage
2 ½ cups (8 ounces) grated Gruyere cheese
Salt and whole white or black pepper in a peppermill
Whole nutmeg in a grater
1. Position a rack in the center of the oven and preheat to 400° F. Generously butter a 10x15 2½-3 quart gratin or baking dish (I use a Le Creuset enameled iron 3-quart gratin dish.)
2. Melt the butter over medium heat in a large skillet. Add the onion and sauté, stirring occasionally, until tender and evenly colored a deep gold, about 10-15 minutes.
3. Meanwhile, peel and thinly slice the potatoes with a sharp knife, mandoline, or food processor. Mix the potatoes with the onion, cream, prosciutto, sage, and 2 cups of Gruyere in a large bowl. Season with salt, pepper, and nutmeg to taste and toss well.
4. Pour into the prepared casserole, pressing down and leveling the top, and sprinkle with remaining cheese. Bake 15 minutes and reduce the heat to 350°. Bake about 1 hour to 1 hour and 15 to 20 minutes longer, or until potatoes are very tender and bubbly at the center and the top is golden brown. Serve hot or warm.