Grate or finely chop the cheese. Cut Halloween patterns out of half of the tortilla rounds.

Spread ketchup on one side of the cut tortillas. Assemble the pizzas in the following order: whole tortilla round - cheese - tortilla round with the pattern, with ketchup on the inside.

Transfer them to a baking sheet lined with parchment paper and place them in an oven preheated to 200°C (392°F). Remove them when the tortilla slightly hardens and the cheese melts, which should take around 5-10 minutes.

Transfer them to a plate.