Zippy Egg Casserole

Ingredients

• 1 pound pork sausage
• 1 (5.5 ounce) package seasoned croutons
• 1 1/2 cups shredded Cheddar cheese
• 1 cup shredded Swiss cheese
• 1 cup shredded pepperjack cheese
• 8 eggs
• 1 pint half-and-half cream
• 1 1/2 cups milk
• 1 1/2 teaspoons dry mustard
• 1 tablespoon minced onion
• salt and pepper to taste