In a bowl, whisk together buttermilk and hot sauce, then add the chicken thighs and coat well. Let marinate for at least 30 minutes for tender, flavorful chicken.
In another bowl, mix flour, paprika, garlic powder, onion powder, salt, and black pepper to create a seasoned dredge.
Remove chicken from the marinade and dredge each piece thoroughly in the seasoned flour, pressing the coating onto the chicken to create a thick crust.
Heat vegetable oil in a cast iron skillet to about 350°F. Fry chicken in batches for 6–8 minutes per side until deep golden brown and crispy.
Transfer fried chicken to a wire rack and let excess oil drain while the crust stays crisp.
In a heat-safe bowl, mix cayenne pepper, brown sugar, smoked paprika, chili powder, garlic powder, and salt. Carefully stir in the hot frying oil to create the spicy chili sauce.
Brush or spoon the hot chili oil over the fried chicken until evenly coated with the bright red spicy glaze.
Serve the hot chicken on slices of white bread topped with dill pickles for a classic Nashville-style presentation.
