Prepare a 9x13-inch baking dish by applying the cooking spray and preheating your oven to 375°F.
Arrange the bread cubes evenly in the dish.
Combine the eggs and milk in a bowl and whisk until they are thoroughly combined.
After adding any desired vegetables and seasoning with salt and pepper, pour the egg mixture onto the bread cubes.
Top the egg mixture with some shredded cheese.
Use aluminum foil to cover the dish and bake it for a duration of 30 minutes.
Uncover the dish by taking off the foil and bake for a further 15-20 minutes, or until the casserole acquires a golden brown hue and solidifies in the middle.
The casserole needs to be cooled down for a short period of time before it can be served.
