In a large bowl, combine buttermilk, garlic powder, onion powder, paprika, salt, and black pepper. Add the chicken thighs, ensuring they are fully submerged. Cover and refrigerate for at least 1 hour, or up to overnight for best flavor.

In another bowl, mix together flour, cornstarch, baking powder, and cayenne pepper (if using).

Remove chicken from buttermilk mixture, allowing excess to drip off, then dredge each piece in the flour mixture, pressing lightly to adhere.

In a large skillet, heat about 1 inch of vegetable oil over medium-high heat until it reaches 350°F.

Carefully add the chicken in batches, frying for about 5-7 minutes per side or until golden brown and cooked through. Use a meat thermometer to ensure the internal temperature reaches 165°F.

Transfer cooked chicken to a paper towel-lined plate to drain excess oil.

In a small bowl, whisk together melted butter, honey, and salt until well combined.

Drizzle the honey butter sauce over the crispy chicken before serving.