Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.
Stir Cheddar cheese, eggs, bacon, bread, red bell pepper, green onion, milk, garlic, salt, and black pepper together in a bowl until well-combined; pour into prepared baking dish.
Bake in the preheated oven until eggs are set, 20 to 25 minutes.
