Prepare and cook the meatballs
Preheat the oven to 450°F. Combine the beef, sausage, parmesan, parsley, egg, garlic, panko, salt, and pepper. Form into small 1/2-inch meatballs and arrange on a foil-lined sheet pan coated with cooking spray. Bake until firm, 6 to 8 minutes. Switch to broil and brown the tops, 2 to 4 minutes.
Tip: Rolling the meatballs with damp hands helps them keep their shape.
Cleanup: Discard the foil after broiling to avoid scrubbing stuck-on bits.