Preheat oven to 400°F (204°C).
Line a baking sheet with parchment paper.
Spread a thin, even layer of shredded parmesan over the parchment.
Use a mandolin to thinly slice 1–2 onions.
Spread the onions evenly over the parmesan cheese.
Lightly spray the top with avocado oil.
Season with salt, black pepper, and garlic powder. Add other seasonings if desired.
Bake for 20 minutes or until golden and crispy.
Let cool completely at room temperature.
Blot any excess oil with a paper towel if needed.
Store in an airtight container at room temperature for several days.
