Cook elbow macaroni according to package directions until al dente, then drain and set aside.
In a large bowl, combine the cooked macaroni, cheddar cheese, Parmesan cheese, milk, melted butter, egg, garlic powder, salt, and black pepper. Mix well.
Scoop the mixture into tablespoon-sized portions and form into bite-sized balls.
Roll each ball in bread crumbs until fully coated and place on a baking sheet lined with parchment paper.
Bake at 375°F (190°C) for 15-20 minutes or until golden brown and crispy.
Serve warm with your favorite dipping sauce.
Notes
For best results, use freshly shredded cheeses and serve immediately after baking.