In a large bowl, beat eggs. Add oats, milk, onion, salt, pepper and garlic powder. Add the ground beef; mix lightly but thoroughly. Shape into 1-1/2-in. balls. Place meatballs on greased racks in shallow baking pans. Bake, uncovered, at 375° for 30 minutes; drain.
Place all of the meatballs in 1 of the pans. In a saucepan, bring all sauce ingredients to a boil. Pour over meatballs. Return to the oven and bake, uncovered, for 20 minutes or until meatballs are done.