Preheat oven to 375 degrees F.
Bring 2 cups of the heavy cream to a simmer in a medium saucepan. Add the potatoes, salt and pepper and cook for 3 minutes.
Rub the cut side of the garlic clove on the bottom and sides of an 8-inch casserole or baking dish. Add the potatoes and cream and top with the remaining cream and Gruyere cheese. Sprinkle chives over top, if using. Bake on a baking sheet until potatoes are tender and cheese is golden brown and bubbly, about 30 minutes. Remove from oven and let rest 10 minutes before serving.
Recipe courtesy of Bobby Flay