Layers of thinly sliced sweet potatoes are baked in a sage-infused cream for this tian, which is a French term for both the style of casserole as well as the shallow earthenware dish it is traditionally baked in. Simple and satisfying, this side dish pairs will pair just as well with a Thanksgiving turkey as it will with a holiday ham.
- 3 tablespoons unsalted butter, softened
- 4 ounces Parmigiano-Reggiano, finely grated (1 cup)
- Kosher salt and freshly ground pepper, plus 7 whole black peppercorns
- 5 cups half-and-half
- 32 fresh sage leaves (from 1 bunch)
- 4 cloves garlic, smashed
- 3 pounds sweet potatoes, such as Jewel, Garnet, or Beauregard, unpeeled
- Extra-virgin olive oil, for drizzling
- Step 1Preheat oven to 375°F. Brush butter evenly over bottom and sides of a 9-by-12-inch oval baking dish, 8-by-10-inch rectangular baking dish, or other shallow 2-to-2 1/2-quart dish. Sprinkle 1/2 cup cheese evenly over butter; season with ground pepper.
- Step 2Combine half-and-half, 20 sage leaves, garlic, and peppercorns in a large saucepan; season with 1 tablespoon salt. Bring to a boil, then reduce heat to medium and simmer until reduced by half, 15 to 20 minutes. Strain, discarding solids; season to taste.
- Step 3Meanwhile, slice sweet potatoes into 1/8-inch-thick rounds. Snugly arrange slices vertically in prepared baking dish. Tuck remaining 12 sage leaves between potatoes; carefully pour half-and-half mixture over top. Sprinkle top with remaining 1/2 cup cheese and lightly drizzle with oil.
- Step 4Roast until potatoes are tender and top is golden brown, 55 to 65 minutes. (If top is browning too quickly, tent with foil.) Let cool at least 15 minutes before serving.