01 - Place chicken breasts between two sheets of plastic wrap and gently pound to an even thickness of about 1/2 inch using a meat mallet or rolling pin.
02 - In a bowl, whisk together the buttermilk, salt, black pepper, and garlic powder until well combined.
03 - Add the pounded chicken breasts to the marinade, turning to coat evenly. Cover and refrigerate for at least 30 minutes, or up to overnight for deeper flavor penetration.
04 - In a shallow dish, combine the all-purpose flour, paprika, cayenne pepper, onion powder, salt, and black pepper. Whisk until uniformly blended.
05 - Pour vegetable oil into a large skillet or deep frying pan to a depth of about 1/2 inch. Heat over medium-high heat until the oil reaches 350°F (175°C).
06 - Remove each breast from the marinade, allowing excess buttermilk to drip off. Dredge thoroughly in the seasoned flour mixture, pressing firmly to ensure the coating adheres on all sides.
07 - Carefully place the breaded chicken into the hot oil, working in batches to avoid overcrowding. Fry for 6 to 7 minutes per side until golden brown and the internal temperature reaches 165°F (74°C).
08 - Transfer the fried chicken to a wire rack or paper towel-lined plate to drain excess oil. Allow to rest for 5 minutes before serving to let juices redistribute.