Preheat your oven to 375.
Line a cookie sheet with a silicone baking matt. I'm guessing the grease from the cheese would soak through parchment paper, rendering it useless.
My cookie sheet had room for two 1/2 cup piles of cheddar cheese. Spread the cheese into a single layer the best you can.
Transfer the cookie sheet to the oven and cook for 6-8 minutes. The longer you cook the cheese the crisper the shell will be.
Take the cookie sheet out of the oven and transfer it to the top of the stove. Allow the cheese to cool for 3-5 minutes before handling.
Take a paper towel and mop off the access grease that will pool on and around the cheese.
Carefully lift the cheese shells off the cookie sheet and transfer them on top of a rolling pin. Lean the rolling pin against another item so it doesn't roll around all over the place.
Allow the cheese to continue cooling for a few minutes then they are ready to use as taco shells!
Stuff the shells with your favorite taco fillings and enjoy!