Cauliflower and Chestnut Gratin
If using fresh chestnuts, score them with an X, then cook them in boiling water until soft, about 20 minutes. Drain and peel the chestnuts.
- Coarse salt
- 1 head cauliflower (about 2 pounds), separated into stems and medium florets
- 2 tablespoons unsalted butter
- 1/3 cup finely chopped shallots
- 2 tablespoons plus 1 teaspoon minced garlic
- Freshly ground pepper
- 1/4 cup dry white wine
- 1 cup homemade or low-sodium store-bought chicken stock
- 1 cup heavy cream
- 1 tablespoon plus 1 teaspoon prepared horseradish
- Freshly grated nutmeg
- 1 tablespoon plus 1 teaspoon fresh thyme leaves
- 1 1/2 cups shelled chestnuts (fresh, jarred, or thawed frozen), halved lengthwise
- 3/4 cup (2 ounces) grated Gruyere cheese
Bring a large pot of water to a boil; add salt. Add florets, and cook until just tender, about 6 minutes. Drain in a colander, and rinse under cold running water until cool. Let dry on paper towels.
Preheat oven to 400 degrees. Finely chop stems to make 1 1/2 cups. Melt butter in a large skillet over medium heat; add stems, shallots, and garlic. Season with salt and pepper. Cook, stirring occasionally, until pale golden brown, about 4 minutes. Add wine, stock, and cream. Simmer, stirring occasionally, until liquid has reduced by about half, 10 to 12 minutes. Let cool slightly. Stir in horseradish, and season with salt, pepper, and nutmeg. Puree mixture in a blender until smooth. Stir in thyme.
Spread florets and chestnuts in a 9-by-12-inch oval gratin dish. Season with salt and pepper. Pour puree on top, and gently stir to combine slightly. Sprinkle with cheese. Bake until bubbling and just golden brown, 30 to 35 minutes.