Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large bowl, combine ground beef, bread crumbs, egg, Parmesan, salt, and pepper. Mix until all ingredients are well combined.
Roll the meat mixture into small balls, about the size of a walnut, and place them on the prepared baking sheet.
Bake in the preheated oven for 12-15 minutes or until cooked through.
Remove meatballs from the oven. Using the sliced olive halves, place two on each meatball to form 'eyes'.
To create the spaghetti 'hair', arrange some cooked spaghetti on top of each meatball. Decorate with ketchup.
Serve warm and enjoy the delightful and monstrous presentation!