In a large bowl, combine the buttermilk, garlic powder, onion powder, smoked paprika, salt, and black pepper. Add the chicken breasts, ensuring they're well coated. Cover and refrigerate for at least 2 hours, preferably overnight for maximum flavor.
In a shallow dish, mix together the flour, panko breadcrumbs, dried thyme, and cayenne pepper (if using). This will create a crispy coating.
Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper for easy cleanup.
Remove the chicken from the marinade, shaking off the excess buttermilk. Dredge each piece in the flour mixture, ensuring they are fully covered. Shake off any excess coating.
Place the coated chicken breasts on the prepared baking sheet. Brush each piece generously with melted butter. Bake in the preheated oven for 20-25 minutes, or until the chicken is golden brown and cooked through (internal temperature should reach 165°F or 74°C).
Once cooked, take the chicken out of the oven and allow it to rest for 5 minutes. This helps to retain moisture. Garnish with freshly chopped parsley before serving.
Notes
For extra flavor, marinate overnight. Serve with garlic mashed potatoes or a fresh garden salad.