If using bacon or sausage, cook meat according to package directions. Chop desired breakfast meat.
Place cubed bread in a 13? x 9? casserole dish and top with breakfast meat and cheese.
Beat eggs, milk, onion powder, salt, and pepper until combined. Pour over casserole ingredients. Let stand for 5 minutes. {You can use your hands to press the bread into the liquid to help the liquid get soaked up.}