Marinate the Chicken: Start by placing the chicken thighs in a large bowl. Pour the buttermilk over the chicken, ensuring they're fully coated. Cover and marinate in the refrigerator for at least 1 hour or overnight for enhanced flavor.
Prepare the Coating: In a separate shallow dish, mix together the flour, garlic powder, onion powder, paprika, salt, and black pepper.
Preheat the Oven: Preheat your oven to 425°F (220°C). If you have a wire rack, place it on a baking sheet to allow hot air to circulate around the chicken.
Coat the Chicken: Remove the chicken from the buttermilk, shaking off any excess. Dredge each piece in the flour mixture, making sure to coat it evenly. Place coated chicken on the wire rack or baking sheet.
Bake: Lightly spray or drizzle the chicken with cooking spray or olive oil. Bake in the preheated oven for 35-40 minutes, or until the chicken is golden brown and reaches an internal temperature of 165°F (75°C).
Serve and Enjoy: Let the chicken rest for a few minutes before serving. Enjoy your crispy oven chicken with your favorite sides!