Step 1: Give that chicken a bath: In a large bowl, whisk together the buttermilk and the egg until they're well combined. Place your chicken pieces into the bowl, making sure they're completely submerged. Cover and refrigerate for at least 2 hours (overnight is best).
Step 2: Whip up the crispy coating: In a shallow dish or large resealable bag, combine the flour, smoked paprika, garlic powder, onion powder, cayenne pepper, salt, and black pepper. Stir or shake to combine.
Step 3: Prep for baking: Preheat your oven to 425°F (220°C). Line a large baking sheet with foil and place an oven-safe wire rack on top. Lightly spray the wire rack with cooking spray.
Step 4: Coat the chicken: Remove chicken from the buttermilk mixture, letting excess drip off. Place one piece at a time into the flour mixture, pressing to get a thick, even coating. Place coated chicken onto the prepared wire rack, leaving space between pieces.
Step 5: Bake 'em up: Bake for 30 minutes. Carefully flip each piece and bake for another 20-30 minutes, or until cooked through (internal temperature 165°F / 74°C) and golden and crispy.
Step 6: Make the hot glaze: While the chicken bakes, melt the butter in a small saucepan over low heat. Stir in the hot sauce, cayenne pepper, brown sugar, smoked paprika, garlic powder, and black pepper. Whisk until combined and warm. Taste and adjust heat if needed.
Step 7: Glaze and serve: As soon as the chicken comes out of the oven, immediately brush each piece generously with the hot oil glaze. Serve hot.