Lightly coat a 3-quart rectangular baking dish with cooking spray; set aside. In a large skillet, cook sausage and mushrooms until sausage is cooked. Drain off fat. Stir red pepper into mixture in skillet; set aside.

Place half of the bread cubes in prepared baking dish. Top with half of the sausage mixture and half of the cheese. Repeat layers with remaining bread cubes, sausage mixture and cheese.

In a large bowl, beat eggs with a rotary beater or whisk. Beat or whisk in milk, mustard, salt and cayenne. Carefully pour egg mixture evenly over bread mixture in dish. Using the back of a spoon, gently press down on layers. Cover and chill at least 2 hours or up to 24 hours.

Bake, uncovered, in a 325 degree F oven for 50 to 60 minutes or until puffed, golden and set. Let stand for 10 minutes before serving. Makes 12 servings.

Prepare as above, except replace sausage with 8 strips of bacon that have been crisp-cooked, drained, and chopped, and replace mushrooms with one 9-oz. package frozen cut asparagus, thawed and well-drained. Combine bacon, asparagus, and red peppers in a medium bowl rather than a skillet. And, use 12 ounces of shredded Swiss cheese in place of the American cheese.