Preheat the oven to 350 degrees F.
Place each of the small tortillas on a baking sheet. Spread 1 teaspoon of the butter on each tortilla. Place the baking sheet into the oven and toast for 8-10 minutes until golden brown. Remove the baking sheet from the oven.
Place 1/4 cup of the Mexican cheese on top of each tortilla and place the baking sheet back into the oven for 3-4 minutes, until the cheese has completely melted. Remove the baking sheet from the oven and top the cheese crisps with the avocado salsa. Serve immediately.