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 shallow bowl, whisk together the buttermilk, salt, black pepper, and garlic powder until well combined.
03 - Submerge the pounded chicken breasts in the buttermilk mixture, turning to coat evenly. Cover and refrigerate for at least 30 minutes, or up to overnight for deeper flavor penetration.
04 - In a separate shallow bowl or dish, combine the all-purpose flour, paprika, cayenne pepper, onion powder, salt, and black pepper. Whisk until evenly distributed.
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. Use a thermometer to monitor the temperature.
06 - Remove each chicken breast from the marinade, allowing excess buttermilk to drip off. Press firmly into the seasoned flour mixture on all sides, ensuring a thorough and even coating.
07 - Carefully lower the coated chicken breasts into the hot oil, working in batches to avoid overcrowding. Fry for 6 to 7 minutes per side until deep golden brown and the internal temperature registers 165°F.
08 - Transfer the fried chicken to a wire rack set over a baking sheet or a paper towel-lined plate to drain excess oil. Allow to rest for 5 minutes before serving to let juices redistribute.