Preheat your oven to 350°F (175°C).
In a large mixing bowl, crack the eggs and whisk them together with the milk, salt, black pepper, garlic powder, and onion powder until well combined and fluffy.
Chop the bell peppers, onion, and parsley (if using). Cube the day-old bread into bite-sized pieces.
Add the diced ham, shredded cheddar cheese, bell peppers, and onion to the egg mixture and stir gently until evenly coated.
Pour the mixture into a greased 9x13-inch baking dish and spread it out evenly.
Bake in the preheated oven for 30-35 minutes, or until set in the center and lightly golden on top.
Let the casserole cool for about 5 minutes before slicing. Garnish with chopped parsley if desired.