Vegetarian Potatoes Au Gratin Potatoes Au Gratin Print Recipe CourseMain Dish CuisineItalian Potatoes Au Gratin Print Recipe CourseMain Dish CuisineItalian Ingredients 6 medium russet potatoes scrubbed, unpeeled and cut into thin slices 8 ounces cheddar cheese shredded 4 ounces Swiss cheese shredded 2 Tablespoons butter 3 Tablespoons flour 2 1/2 cups Milk 2 Tablespoons Dijon mustard 1/4 teaspoon salt 1/4 teaspoon pepper Servings: Instructions Preheat oven to 400 degrees F Coat a 13x9-inch baking dish with nonstick cooking spray. Layer potatoes in prepared dish. Top with cheeses. Melt butter in medium saucepan over medium heat; stir in flour; cook 1 minute. Stir in milk, mustard, salt and pepper; bring to a boil. Reduce heat and cook, stirring constantly, until mixture thickens. Pour mixture over cheese. Cover with foil. Bake 30 minutes. Remove foil and bake 15 to 20 minutes or until potatoes are tender and top is brown.