Preheat oven to 400 degrees. Spray your 12 muffin tin pan with nonstick spray.
Unroll your pie crust and use a rolling pin to flatten a bit so the crust is between 1/8" to 1/4" thick.
Use your 3" round cookie cutter to make 12 circles of dough. You may need to re-roll crust scraps.
Place each pie round inside a muffin tin cavity and lightly press up on the sides. Prick with a fork.
Add 1 teaspoon of sauce on top of each muffin tin cavity.
Bake in the oven for about 15 minutes until the cheese is bubbly and the sides of pie are crisp. Take out of the oven and allow to cool before removing.
Next, cut the white mozzarella cheese slices into ghost shapes.
Once the muffin tin pizzas are done baking, add in more pizza sauce and then the cheese immediately on top so it can start melting a bit.
Adding olive eyes or candy eyes is optional. We didn't have any on hand, so we added some illustrated eyes for fun.