1/2 stick butter melted in 9 x 13 inch pan. Crumble 5 slices of bread in pan. Brown 1 pound sausage. Drain fat. Mix together 6 eggs, 2 cups milk, 1/4 teaspoon mustard, salt and pepper to taste. Sprinkle sausage on bread. Sprinkle 6 ounces grated Cheddar cheese on sausage. Pour egg mixture over top. Bake at 375 degrees for 45 minutes.