01 - Combine buttermilk, garlic powder, onion powder, salt, and black pepper in a mixing bowl. Add chicken fillets, ensure even coating, cover, and refrigerate for at least 15 minutes.
02 - In a shallow dish, mix together flour, panko breadcrumbs, and grated Parmesan cheese. In a separate bowl, beat the eggs until smooth.
03 - Remove marinated chicken from the refrigerator. Coat each fillet in the flour mixture, dip into beaten eggs, then return to the flour mixture for a second coating.
04 - Heat 1/2 inch of vegetable oil in a skillet to 350°F. Fry chicken fillets for 3 to 4 minutes per side until golden and internal temperature reaches 165°F. Transfer to paper towels to drain excess oil.
05 - Toss shredded romaine lettuce with Caesar dressing in a bowl. Add shaved Parmesan cheese and combine gently.
06 - Spread optional butter on cut sides of buns and toast in a skillet until golden brown.
07 - Place one fried chicken fillet on each bun base. Top with dressed romaine and Parmesan mixture. Cap with the other bun half and serve immediately.