Preheat oven to 375°F (190°C). Grease a 9x13 inch baking dish.
In a large skillet, cook the breakfast sausage over medium heat until browned and crumbled. Drain off excess grease. Add the chopped onion and bell peppers to the skillet and cook until softened, about 5-7 minutes. Remove from heat.
1.5 pounds breakfast sausage
In a large bowl, whisk together the eggs, milk, salt, pepper, and garlic powder until well combined.
1.5 pounds breakfast sausage
Add the cooked sausage and vegetable mixture, shredded cheddar cheese, and crumbled cream cheese to the egg mixture. Stir to combine.
1.5 pounds breakfast sausage
Gently fold in the cubed everything bagels.
1.5 pounds breakfast sausage
Pour the mixture into the prepared baking dish. Sprinkle the everything bagel seasoning evenly over the top.
1.5 pounds breakfast sausage
Bake for 40-50 minutes, or until the casserole is set and golden brown. Let stand for 5-10 minutes before serving.
Notes
This casserole can be assembled the night before and refrigerated. Bake as directed, adding a few extra minutes to the cooking time if baking from cold.