Arrange bread cubes in a single layer on a baking sheet.
Bake at 400 for 8 minutes or until toasted.
Heat a medium skillet over medium-high heat. Coat pan with cooking spray.
Add sausage to pan; cook 6 minutes or until browned, stirring to crumble.
Combine sausage, bread, and onions in a large bowl.
Combine milk, cheese, eggs, and egg substitute in a medium bowl, stirring with a whisk.
Add milk mixture to bread mixture, tossing to coat bread. Spoon mixture into a 2-quart baking dish coated with cooking spray. Cover and refrigerate 8 hours or overnight.
Preheat oven to 35
Uncover casserole.
Bake at 350 for 50 minutes or until set and lightly browned.
