How to Make It
Cook sausage 8 minutes in a skillet over medium-high heat, stirring to crumble. Toss together sausage, Parmesan, and next 3 ingredients; arrange in a 13- x 9-inch baking dish coated with cooking spray.
Whisk together milk and next 2 ingredients; pour over sausage mixture. Cover and chill 8 hours.
Preheat oven to 350°. Uncover casserole, and sprinkle with Gruyère. Bake 45 minutes or until golden. Let stand 10 minutes.