Potato Gratin with Juniper

Put oven rack in middle position and preheat oven to 375 °F. Finely grind juniper berries in grinder. Whisk together cream, butter, 1 1/4 teaspoons ground juniper (discard remainder), salt, and pepper in a large bowl until combined. Peel potatoes and cut into 1/8-inch-thick slices. Fold potato slices into cream mixture and transfer to baking dish, spreading evenly. Cover tightly with foil and bake until potatoes are very tender, 50 minutes to 1 hour. Preheat broiler. Remove foil and broil potatoes 2 to 3 inches from heat until golden, about 6 minutes. Let stand 10 minutes before serving. *Available in the spice section of some supermakets.