Cover rimmed baking sheet with foil; spray with cooking spray. Mix beef, pork, coating mix, ketchup, cheese, egg and 1/4 cup onions just until blended.
Shape into 32 meatballs, using about 1 Tbsp. meat mixture for each meatball.
Place on prepared baking sheet.
Bake 20 to 25 min. or until done (160ºF).
Meanwhile, prepare potatoes as directed on package. While potatoes are cooking, heat oil in large nonstick skillet on medium heat. Add remaining onions; cook and stir 3 min. or until crisp-tender. Add gravy, cream and Worcestershire sauce; mix well. Cook 3 min. or until heated through, stirring frequently.
Serve meatballs over potatoes topped with gravy mixture.