Preheat Oven: Set oven to 375°F and grease a 9x13-inch baking dish.
Cook Turkey Bacon: In a skillet, cook turkey bacon until crisp. Let cool, then crumble into small pieces.
Whisk Eggs: In a large bowl, whisk together eggs, milk, salt, pepper, and onion powder until smooth.
Mix Ingredients: Stir in shredded cheese, veggies, turkey bacon, and optional bread cubes.
Assemble Casserole: Pour mixture into the greased baking dish and spread evenly.
Bake: Bake for 30–35 minutes, or until the edges are golden and the center is set.
Cool and Serve: Let the casserole rest for 5 minutes before slicing into portions.