Meatball recipe

1 pound lean ground beef 1 pound ground pork (or additional ground beef) ½ cup Italian bread crumbs ⅓ cup milk ¼ cup finely diced onion ¼ cup chopped fresh parsley (or 1 tablespoon dried parsley) ¼ cup grated Parmesan cheese 1 large egg 1 teaspoon Italian seasoning ½ teaspoon garlic powder ½ teaspoon salt (more to taste) ½ teaspoon black pepper