Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13 inch baking dish.
In the prepared baking dish, layer the cubed bread, diced ham, and shredded cheddar cheese.
In a separate bowl, whisk together the eggs, milk, salt, pepper, and garlic powder until well combined.
Pour the egg mixture evenly over the bread, ham, and cheese mixture. Gently press down to ensure the bread is soaked.
Cover the dish with foil and bake for 25 minutes.
Remove the foil and bake for an additional 15-20 minutes, or until the casserole is puffed and golden brown, and a knife inserted into the center comes out clean.
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 covered baking time if baking from cold.