Like any gratin worth its name, this is very rich and sweet from the apples and sweet potatoes. And like most savory, apple-based dishes, it is very good with sausage, which is how I served it. It does take a little time to assemble, about 45 minutes, but once you've put it in the oven you'll have an hour or so to leave it undisturbed. It also makes it a very good Sunday supper, as it cooks while you pay bills, catch up on television, or pad around the house in pajamas. Once it comes out of the oven, you can sit down to your rich winter meal, staving off that impending Monday-morning feeling.
Serves 2, with leftovers
(adapted from Dan Barber)
• 8 tablespoons unsalted butter
• 1 1/2 pounds tart apples (about 3 or 4 fist-sized apples)
• 1/2 cup heavy cream
• 1/2 cup whole milk (don't be tempted to substitute something lower in fat; if you do, the resulting liquid will separate)
• 2 teaspoons salt
•1 teaspoon white pepper
• 1/2 teaspoon cinnamon
• large pinch ground nutmeg
• 2 1/2 pounds sweet potatoes (about 3 or 4 large ones)
•1 clove garlic, crushed
• 1/2 cup panko or fresh bread crumbs
Peel and core the apples, then quarter them and slice thinly. Peel the sweet potatoes and cut them into ¼-inch-thick rounds.
Preheat your oven to 350 degrees.
In a 12-inch sauté pan, lightly brown 2 tablespoons of butter over medium heat. Add as many of the apple slices as will fit without crowding, and then sauté them until lightly browned, making sure they stay firm. Set the apples aside on a plate. Repeat with 2 more tablespoons of butter and the remaining apples. (Depending on the size of your pan, you may need to do more than two batches of apples. If that's the case, just make sure that when you remove the previous batch, there's still enough butter in the pan so that the next batch won't burn. The only thing limiting your use of butter, really, is your concern for your cardiac health.)
In a large bowl, stir the cream, milk, salt, pepper, cinnamon, and nutmeg until the salt has dissolved. Toss the potatoes in the cream to coat.
Generously butter an 8x8x2-inch ovenproof dish or an 8-inch cake pan, and rub with the crushed garlic. Line the bottom of the dish with a layer of overlapping sweet potatoes, followed one of apples. Cover with another layer of sweet potatoes. Pour in the remaining spice-cream mixture.
Cover with aluminum foil, and bake for about one hour, or until the potatoes are cooked. Heat the broiler. Sprinkle panko over the gratin, dot with 1/4-inch cubes of the remaining butter, and broil a few minutes until the bread crumbs are golden brown. (This is really the one moment where you have to keep a watchful eye on the gratin--the breadcrumbs will burn quickly if you're not careful.)