Preheat your oven to 425°F (220°C). Line a baking sheet with aluminum foil or parchment paper for easy cleanup.
Pat the chicken thighs dry with paper towels to ensure crispy skin.
In a small bowl, mix together the olive oil, garlic powder, onion powder, smoked paprika, dried thyme, salt, black pepper, and cayenne pepper (if using).
Rub the spice mixture all over the chicken thighs, making sure to get it under the skin for maximum flavor.
Place the chicken thighs skin-side up on the prepared baking sheet.
Bake in the preheated oven for 35-40 minutes, or until the internal temperature reaches 165°F (74°C) and the skin is crispy.
Let the chicken rest for 5 minutes before serving to allow the juices to redistribute.