01 - In a mixing bowl, combine buttermilk, garlic powder, onion powder, salt, and black pepper. Submerge chicken fillets in the mixture, cover, and refrigerate for a minimum of 15 minutes or up to 4 hours for enhanced tenderness.
02 - In a shallow dish, combine all-purpose flour, panko breadcrumbs, and grated Parmesan cheese. In a separate bowl, whisk the eggs until fully combined.
03 - Remove chicken fillets from marinade. Dredge each fillet in the flour mixture, followed by the beaten eggs, then return to the flour mixture, ensuring an even and thorough coating.
04 - Pour vegetable oil into a skillet to a depth of 1/2 inch and preheat to 350°F. Fry chicken fillets 3 to 4 minutes per side until golden brown and cooked through. Drain excess oil on paper towels.
05 - Gently toss shredded romaine lettuce with Caesar dressing in a mixing bowl. Incorporate shaved Parmesan and mix lightly.
06 - If desired, spread butter on the cut sides of each bun and toast until golden. Layer fried chicken fillet onto the bottom half of each bun, top with prepared Caesar salad, and cover with the remaining bun halves.
07 - Present sandwiches at once, optionally garnished with extra Caesar dressing or lemon wedges.