Position racks in upper and lower thirds of oven; preheat to 450°F. Line 2 large rimmed baking sheets with foil and coat with cooking spray.
Combine eggs, onion, panko, parsley, Parmesan, garlic, Italian seasoning, salt and pepper in a large bowl. Add beef and pork. Mix gently with your hands until just combined (do not overmix). Using a generous 2 tablespoons each, shape into 48 meatballs. Place 1 inch apart on the prepared baking sheets.
Bake the meatballs until an instant-read thermometer inserted in the center registers 165°F, about 15 minutes.