A rich mixture of baking and sweet potatoes, this will soon become a favorite make-ahead party dish. Jean, the author of Process This!: New Recipes for the New Generation of Food Processors plus Dozens of Time-Saving Tips, simplified this recipe using a food processor. The slicing disk on your processor will yield quick, thin potato slices. By slicing the two kinds of potato together, they're "ready-mixed." If you don't have a food processor, slice the potatoes by hand. (It will yield a thicker slice but will work just as well.) This gratin is equally delicious with baked ham, roast beef, pork, turkey, or chicken. Prep: 15 minutes, Cook: 3 minutes, Bake: 45 minutes.
2 large garlic cloves
1 1/2 teaspoons rubbed sage
1 teaspoon dried thyme, crumbled
1 teaspoon salt
1/2 teaspoon freshly ground pepper
2 tablespoons flour
2 cups half-and-half
3 medium baking potatoes (1 1/2 pounds), peeled and thinly sliced
1 large sweet potato (1 pound), peeled, halved lengthwise, if desired, and thinly sliced
2 tablespoons butter, diced
3 tablespoons freshly grated Parmesan cheese
How to Make It
Preheat oven to 425°. Process first 5 ingredients in a food processor fitted with the chopping blade, 3 to 5 seconds or until garlic is finely chopped. Pulse in flour and 1/2 cup half-and-half, then pulse in remaining half-and-half. Transfer to a medium saucepan.
Remove chopping blade from the processor, and insert medium slicing disk. Stand chunks of baking and sweet potato side by side in feed tube, and pulse through the disk. Repeat until all potatoes are sliced. Spread half the potatoes in a lightly greased shallow 2-quart baking or gratin dish.
Cook cream mixture over high heat, stirring constantly, for 3 minutes or until it starts to boil. Pour half the boiling cream mixture evenly on top of potatoes; add remaining potatoes, and repeat with remaining cream mixture. Dot with butter.
Note: At this point, you can cover the dish with foil and refrigerate for several hours. Before baking, let stand for 30 minutes at room temperature, and bake, uncovered.
Bake at 425° on the middle oven rack for 35 minutes or until potatoes are crusty-brown on top and tender underneath. Sprinkle cheese on top, and bake 10 more minutes.