1. preheat oven to 375 degrees
2. place milk, leek, salt, pepper, potato, thyme, bay leaf, and garlic in a dutch oven; bring to a boil. cover, reduce heat, and simmer 10 minutes or until potatoes are tender. discard thyme and bay leaf
3. spoon half of the potato mixture into a 13x9-inch baking dish coated with cookking spray. sprinkle with 1/2 cup cheese. top with remaining potato mixture and remaining 1/2 cup cheese. bake at 375 * for 1 hour or until golden brown. let stand for 10 minutes before serving.