Heat the oven to 350°F. Lightly oil a 10 x 13-inch (or 10-inch round) baking dish. Combine the meat, egg, onion, milk, breadcrumbs, salt, and pepper in a large bowl. Shape the mixture into a 10-inch round dome and place it in the baking dish. Mix the 1/3 cup ketchup, 2 tablespoons brown sugar, and 2 tablespoons prepared mustard in a small bowl until blended. Spread the mixture over the meatloaf. Bake for 1 hour. Transfer the meatloaf to a wire rack and let rest for 20 minutes.
Cook the pappardelle according to the package directions; drain and keep warm while meatloaf rests.
To make the sauce:
1. Combine all the ingredients in a small saucepan. Cook over medium heat, stirring, until bubbly and thickened, about 3 minutes. Keep warm until ready to serve.
Remove the meatloaf from the pan and place on a serving plate. Cut the mozzarella ball in half. Layer the pasta strands one by one over the meatloaf to look like a mummy’s wrappings, adding the mozzarella and two olives for eyes as shown. Surround the meatloaf with more olives. Serve with the sauce on the side.