Preheat your oven to 400°F. Line a baking sheet with parchment paper. Make sure you use parchment paper and not wax paper, as wax paper will smoke and burn in the oven.

Make small mounds of shredded cheese on the parchment paper, using about 2 tablespoons of cheese per mound. Space them about 3 inches apart because they will spread as they melt and you don't want them touching.

Press one pepperoni slice gently onto the top of each cheese mound. If you're using optional seasonings like Italian seasoning, garlic powder, or red pepper flakes, sprinkle them on now before baking.

Place the baking sheet in the preheated oven and bake for 8 to 10 minutes. Watch them carefully during the last few minutes. The crisps are ready when the edges are golden brown and bubbling, and the cheese looks lacy and crispy around the edges.

Remove the baking sheet from the oven and let the pepperoni and cheese crisps sit on the pan for at least 5 minutes without touching them. They will firm up and become crispy as they cool. Don't try to remove them too early or they'll tear and fall apart.

Once completely cooled, the crisps will easily pop off the parchment paper. If any stick, use a thin spatula to gently lift them. They should release cleanly if you've waited long enough for them to cool.

Store the cooled pepperoni and cheese crisps in an airtight container at room temperature for up to 3 days. Don't refrigerate them or they'll lose their crispiness. If they soften, you can re-crisp them in a 350°F oven for 2 to 3 minutes.