Grease a 9x13-inch dish with butter or cooking spray.
Layer half the bread, half the bacon, and half the cheese in dish; repeat with remaining ingredients.
Whisk eggs, milk, cream, mustard, salt, pepper, and garlic powder in a large bowl until combined.
Pour evenly over bread layers; press gently to soak all bread.
Cover tightly with plastic wrap; refrigerate at least 8 hours or overnight.
Next morning, remove from refrigerator; stand at room temperature 20 minutes. Preheat oven to 350°F.
Remove plastic wrap; bake uncovered 45-50 minutes until golden brown and center set.
Stand 10 minutes before cutting squares and serving.