Adjust oven rack to lower-middle position; heat oven to 375℉.
Wrap tortillas in a damp paper towel. Microwave on high for 30-45 second to soften.
Lightly brush both sides of each tortilla with the melted butter. If you're making the dessert bowls, mix together the cinnamon and sugar in a small bowl. Sprinkle the mixture on both sides over the melted butter.
Firmly press each tortilla into a small oven-safe bowl or jumbo muffin tin.
Bake at to 375℉ 12-15 minutes, until the tortillas are crispy and browning around the edges.
Immediately transfer the tortilla bowls to a wire rack. Cool completely before serving, about 15 minutes.