Brown the ground beef in a large skillet over medium heat. Add the diced onion, carrots, and garlic. Cook until the vegetables soften.
Stir in the tomato paste, beef broth, Worcestershire sauce, and peas. Simmer for 10 minutes until the mixture thickens. Season with salt and pepper, then transfer to a baking dish.
Boil the potatoes in a large pot of salted water until tender. Drain and return them to the pot.
Mash the potatoes with the butter and milk until smooth. Add salt and pepper to taste.
Spoon the mashed potatoes over the filling. Use a spoon or piping bag to shape the top into 4 to 6 ghost forms.
Press two olive halves into each ghost to make eyes. Bake at 400 degrees Fahrenheit for 20 minutes until the edges turn golden.