Tear one hot dog bun into bite sized pieces and set aside to use as a binding agent.
Combine the pieced hot dog bun, beef, sausage, garlic, onion, egg, basil, parsley, parmesan, milk, salt and pepper in a bowl and mix well. Scoop mixture by tablespoons and shape into little balls (1-inch). Place on a cookie sheet and place in freezer for 15 minutes to firm up.
In a pot, heat the oil and cook meatballs in batches until browned but not cooked all the way through. Add all browned meatballs back to the pot and cover with the sauce. Allow the meatballs to cook completely and the sauce to heat thoroughly.
Place hot dog buns on a serving plate. First place mozzarella cheese on the bottom of each bun, then spoon meatballs and heated sauce on top of the cheese. Sprinkle olives and Parmesan on the meatballs and sauce, followed by the remaining mozzarella cheese.
Serve warm and enjoy!