1 pound (450 g) lean ground beef
1/2 cup (125 ml) Parmesan cheese
1/4 cup (60 ml) panko bread crumbs
1 egg, lightly beaten
1 tablespoon (15 ml) garlic powder
1 tablespoon (15 ml) dried oregano
1 tablespoon (15 ml) dried basil
1 tablespoon (15 ml) onion powder
1 tablespoon (15 ml) fresh parsley, chopped
1 tablespoon (15 ml) Worcestershire sauce
3 - 4 mozzarella cheese sticks, cut into 1/2" pieces
Salt, to taste
Pepper, to taste
Arrange the cut mozzarella cheese sticks in a single layer on a baking sheet. Place in the freezer for 30 minutes.
Combine the ground beef, panko bread crumbs, Parmesan cheese, egg, garlic powder, onion powder, oregano, basil, Worcestershire sauce, salt, and pepper in a large bowl. Using your hands, mix all ingredients thoroughly. Scoop out about 3 tablespoons of meat mixture, shape into a meatball, and set aside on a baking sheet.
After meatballs are all formed and mozzarella sticks are slightly frozen, remove the cheese from the freezer. One at a time, gently push one of the cheese stick pieces into one meatball so it sits in the center of the meatball. Seal up the sides so that the cheese is completely encased. Repeat with the remaining meatballs.
Grease a 6-quart slow cooker with non-stick cooking spray, or place sauce inside, if using. Place meatballs inside, cover the slow cooker with the lid, and set to low. Cook for 4 hours, or until the meat is completely cooked through and no longer pink inside.