Name: Pommes Duchesse Gratin
Cook time: 25 min
Total time: 2 hr
Yield: Makes 8 servings
Ingredients: 3 lb russet (baking) potatoes; 1 cup heavy cream; 5 tablespoons unsalted butter; 1 garlic clove, minced; 3 large eggs; 1 1/4 teaspoons salt; 1/4 teaspoon white pepper; 3/4 teaspoon freshly grated nutmeg; a potato ricer or a food mill fitted with medium disk

Traditionally piped through a pastry bag into rosettes to garnish a roast, this classic French potato mixture is here transformed into a rich casserole that can be prepared in advance and is still the perfect match for a prime rib roast.

Cooks' notes:

·Gratin can be prepared (but not baked) 1 day ahead and cooled completely, uncovered, then chilled, its surface covered with buttered wax paper and dish wrapped in plastic wrap. Bring to room temperature, about 1 hour, before baking.
·If you have only one oven, bake gratin while rib roast stands.