01 - Place each chicken breast between two sheets of plastic wrap. Pound to an even thickness of approximately 1/2 inch using a meat mallet.
02 - Whisk together buttermilk, salt, black pepper, paprika, and garlic powder in a shallow bowl. Add chicken breasts, turning to coat thoroughly. Marinate for at least 15 minutes, up to 2 hours for optimal flavor development.
03 - Prepare three shallow bowls: one with flour, one with beaten eggs mixed with Dijon mustard, and one with panko, Parmesan, and oregano combined.
04 - Remove chicken from marinade, allowing excess to drip off. Dredge each breast first in flour, then in the egg mixture, and finally in the panko-Parmesan mixture, pressing gently to ensure thorough coating.
05 - Heat oil in a large skillet over medium-high heat until reaching 350°F. Add chicken breasts in batches if necessary. Fry for 3-4 minutes per side until golden brown and cooked through to an internal temperature of 165°F.
06 - Transfer fried chicken to a paper towel-lined plate to drain excess oil. Let rest for 2 minutes before serving to allow juices to redistribute.