01 - Combine buttermilk, garlic powder, onion powder, salt, and black pepper in a bowl. Submerge chicken fillets in the mixture, cover, and refrigerate for at least 15 minutes or up to 4 hours.
02 - In a shallow dish, mix together flour, panko breadcrumbs, and grated Parmesan cheese. Beat eggs in a separate bowl.
03 - Remove chicken from marinade. Coat each fillet in the flour mixture, then dip in beaten eggs, then return to the flour mixture for a double coating.
04 - Heat 1/2 inch of vegetable oil in a skillet to 350°F (175°C). Fry coated chicken fillets for 3 to 4 minutes per side until golden and cooked through. Drain excess oil on paper towels.
05 - In a mixing bowl, toss shredded romaine with Caesar dressing. Add shaved Parmesan and gently combine.
06 - If desired, spread butter on the cut sides of each bun and toast in a skillet until golden brown.
07 - Place one fried chicken fillet on the bottom half of each toasted bun. Top with Caesar salad and finish with the top bun.
08 - Serve immediately, with additional Caesar dressing or lemon wedges if desired.