Mix together the beef, eggs, bread crumbs, garlic, Worcestershire sauce, parmesan cheese, onion powder and other seasonings together in a bowl, mixing until well combined.
Using a scoop or meatballer, place two scoops of meat into your hand and press to form sixteen burger patties; place onto a large platter.
After slicing fillings (if needed), place filling ingredients in the center of eight patties.
Take the eight plain patties and place them on top of the filled patties, massaging together the ends so no seam remains.
Form and press a little further so each finished burger is uniform in size and shape; grill until cooked to 170.
Upon removing it from the grill's flame, place onto a bun and immediately sprinkle with mozzarella cheese.