Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
In a mixing bowl, combine the grated cheddar cheese, grated parmesan cheese, breadcrumbs, garlic powder, onion powder, salt, and black pepper. Mix well.
Heat olive oil in a skillet over medium heat. Add the thinly sliced onions and sauté until they become translucent and lightly caramelized, about 5-7 minutes. Remove from heat.
Let the sautéed onions cool slightly, then fold them into the cheese mixture until well combined.
Scoop spoonfuls of the mixture onto the prepared baking sheet, flattening them into thin rounds.
Bake in the preheated oven for about 20-25 minutes or until the edges are golden brown and crispy.
Remove from the oven and allow to cool for a few minutes. They will become crispier as they cool.
Garnish with fresh parsley before serving.