Combine ground beef, breadcrumbs, egg, Parmesan, garlic, Italian seasoning, salt, and pepper. Shape into 12 small meatballs.
Heat olive oil in a skillet and brown the meatballs on all sides. Add marinara sauce, cover, and simmer for 12–15 minutes until cooked through.
Meanwhile, boil the spaghetti in salted water according to package directions. Drain and toss with enough marinara to coat thoroughly.
Cut mozzarella slices into rounded ghost shapes, leaving irregular flowing edges near the bottom.
Arrange spaghetti and meatballs on serving plates. Place the cheese ghosts over several hot meatballs or small mounds of pasta.
Allow the heat to soften the cheese slightly, then add tiny black olive pieces for eyes and different mouth expressions.