Preheat the oven to 400 degrees. In a mixing bowl combine the ground beef, breadcrumbs, egg, Italian seasoning, salt, and black pepper until evenly mixed.
Shape the mixture into 12 meatballs and place them on a baking sheet. Bake for 15 to 18 minutes until the centers reach 160 degrees.
While the meatballs bake, pour the marinara sauce into a large skillet and warm it over medium heat.
Add the cooked meatballs to the skillet and turn them gently to coat with sauce. Let them simmer for 3 minutes.
Place one mozzarella round on each meatball, then set an olive half in the center of the cheese to form the eye.