Preheat over to 325 degrees F.
Spray an 8-inch square baking dish with nonstick spray.
Cube English muffins, and add half in a single layer in baking dish.
Top with half of the cooked sausage and 1/2 cup of the cheese.
Layer the remaining English muffins, sausage and remaining cheese.
Whisk together the eggs, milk, salt, and pepper in a medium bowl.
Pour the egg mixture evenly over the casserole.
Cover the dish with plastic wrap and refrigerate for at least an hour, but can be left overnight.
Bake 45 to 50 minutes or until eggs are set.