Preheat your oven to 425°F (220°C). Line a baking sheet with aluminum foil or parchment paper for easy cleanup.
In a large bowl, combine the olive oil, garlic powder, onion powder, smoked paprika, dried oregano, salt, black pepper, and cayenne pepper (if using). Mix well to form a marinade.
Add the chicken thighs to the bowl and toss them in the marinade until they are evenly coated. Let them marinate for at least 15 minutes at room temperature, or refrigerate for up to 2 hours for more flavor.
Arrange the marinated chicken thighs skin-side up on the prepared baking sheet, making sure they are not touching each other.
Bake in the preheated oven for 35-40 minutes, or until the skin is crispy and the internal temperature reaches 165°F (74°C).
For extra crispiness, broil the chicken thighs for an additional 2-3 minutes at the end of baking, watching closely to prevent burning.
Remove from the oven and let rest for 5 minutes before serving.