Make the ghost pizza by cutting out 2 ghost shapes from 2 of the cheese slices and putting the on one of the pizza bases. Use a black olive to make little eyes and finely chop another black olive to spell out boo. Cook the pizza in the oven according to the cooking instructions on the packet.
To make the mummy pizza, use the off cuts from the ghost pizza and cut the cheese in to strips to create a mummy face. Use olives to make eyes. Cook the pizza in the oven according to the cooking instructions on the packet.
To make the vampire pizza, chop one of the slices of ham in to strips to make the hair, and the other slice to make a mouth with fangs. Use and olive to make eyes. Cook the pizza in the oven according to the cooking instructions on the packet.
Notes
Why not use strips of courgette to make the mummy, instead of just cheese. This is a good way to give the pizzas a veggie boost.