HEAT oven to 375°F.
COOK sausage in large skillet on medium-high heat 5 to 7 min. or until done, stirring frequently.
MEANWHILE, prepare Dinner in large saucepan as directed on package. Stir in sausage, onions, green peppers, milk, egg and black pepper.
SPOON into 8-inch square baking dish sprayed with cooking spray. Top with cheeses.
BAKE 20 min. or until heated through.