Preheat oven to 400 degrees and line a baking sheet.

Spread each muffin half with pizza sauce.

Cut ghost shapes from the mozzarella slices using a small knife or cookie cutter and place one on each muffin.

Add two olive slices to each ghost for eyes.

Bake 10 to 12 minutes until the cheese melts and the edges crisp, then cool slightly before serving.