Make Taco Shells With Tortillas. Working with 6 tortillas at a time, wrap in a barely damp cloth or paper towel and microwave on High until steamed, about 30 secs. Lay the tortillas on a clean work surface and coat both sides with cooking spray. Then carefully drape each tortilla over two bars of the oven rack. Bake at 375 F until crispy, 7 to 10 minutes.