01 - If the chicken breasts are uneven in thickness, place each one between two sheets of plastic wrap and gently pound with a meat mallet to a uniform ½-inch thickness.
02 - In a large mixing bowl, whisk together the buttermilk, egg, kosher salt, black pepper, garlic powder, and paprika until fully combined.
03 - Submerge the chicken breasts in the marinade, turning to coat evenly. Cover and refrigerate for at least 30 minutes, or up to 4 hours for deeper flavor penetration.
04 - In a shallow dish, combine the flour, panko breadcrumbs, salt, smoked paprika, and cayenne pepper. Mix well. Remove the chicken from the marinade, letting any excess drip off.
05 - Dredge each marinated chicken breast in the flour-breadcrumb mixture, pressing firmly on all sides so the coating adheres completely. Shake off any loose breading.
06 - Pour the vegetable oil into a large skillet or deep frying pan and set over medium-high heat. Heat until the oil shimmers and reaches 350°F on an instant-read thermometer.
07 - Carefully lay the breaded chicken breasts into the hot oil. Fry for 5 to 7 minutes per side until deeply golden and crispy, and the internal temperature reads 165°F at the thickest part.
08 - Transfer the fried chicken to a paper towel-lined plate to drain excess oil. Let rest for 2 to 3 minutes before slicing and serving.