Potato-And-Cheese Purée

This a French peasant dish; a rich and indulgent treat that is comforting and delicious.

• Ready In: 50 mins
• Serves: 6

Ingredients

• 2  lbs yukon gold potatoes (6 medium)
• 4  garlic cloves
• 1 1⁄4 teaspoons salt
• 3  tablespoons butter, softened
• 3⁄4 cup  whole milk
• 3⁄4 lb cantal cheese (5 cups) or 3⁄4 lb gruyere cheese, coarsely grated on large holes of a box grater (5 cups)
• 1⁄2 teaspoon black pepper
• 2⁄3 cup  chilled heavy cream
• 2  tablespoons  drained bottled horseradish

Directions

1. Peel and cube potatoes cover with salted water in a 4- to 5-quart heavy pot and simmer until very tender. Drain in a colander. While potatoes cook, mince garlic and mash to a paste with 1 teaspoon salt using side of a large heavy knife.
2. Put potatoes through a ricer into the saucepan or mash really well by hand or use your KA mixer with the paddle, then put back in the pot. Add butter, garlic paste, and milk and cook over moderately low heat, stirring vigorously with a wooden spoon, until fluffy and heated through, about 2 minutes. Add cheese and pepper and cook, stirring vigorously with a heatproof rubber spatula or wooden spoon, until cheese is melted, smooth, and almost taffylike, about 10 minutes.
3. Preheat broiler. Butter baking dish. (If using 6 individual gratin dishes, butter and put on a baking sheet.) Transfer potato mixture to baking dish, smoothing top.
4. Beat cream in a bowl with an electric mixer until it holds soft peaks, then beat in horseradish and remaining 1/4 teaspoon salt. Spread horseradish cream over potato mixture and broil 4 to 5 inches from heat, rotating gratin if it isn't browning evenly, until golden, 1 to 2 minutes.