Rub an 11 x 7 inch baking dish with the garlic and discard the garlic. Coat the dish with butter. In a large skillet, combine the milk and the next 5 ingredients, through the potatoes. Bring to a simmer and cook for 8 minutes until the potatoes are almost tender. Spoon potatoes mixture into the baking dish, including the milk. Sprinkle with cheeses. Bake at 375° for 35 minutes or until golden brown. Let stand for 10 minutes before serving. Serves 8.