Place potatoes in a large saucepan and cover with water.
Bring to a boil, then reduce the heat to low. Cook for about 15 min., or until soft. Drain the water, then add the milk, garlic, cream cheese, salt and pepper. Mash with a potato masher or beat with an electric mixer until creamy and lump-free.
Scoop the potatoes into a pastry bag without a decorator's tip. Squeeze the ghosts onto a lightly buttered cookie sheet so they stand upright. To create ghastly eyes, press two even-sized black beans (or peas) into each ghost's head.