01 - In a large mixing bowl, whisk buttermilk with garlic powder, onion powder, salt, and black pepper. Submerge chicken fillets, cover, and refrigerate for at least 15 minutes or up to 4 hours.
02 - In a shallow dish, combine all-purpose flour, panko breadcrumbs, and grated Parmesan. In a separate bowl, beat the eggs until well blended.
03 - Remove the chicken fillets from marinade, allowing excess to drip off. Coat each piece in flour mixture, then dip in beaten eggs, and return to the flour mixture for a second coating to ensure maximum crispiness.
04 - Pour vegetable oil into a skillet to a depth of 1/2 inch and heat to 350°F. Fry chicken fillets for 3–4 minutes per side until golden and internal temperature reaches 165°F. Drain on paper towels.
05 - In a bowl, toss shredded romaine with Caesar dressing. Add shaved Parmesan and gently mix to combine.
06 - If desired, spread butter on cut sides of buns and toast in a skillet or under broiler until golden brown.
07 - Place one fried chicken fillet on the bottom half of each bun. Top with Caesar salad and cover with the toasted top bun.
08 - Serve immediately, with additional Caesar dressing or lemon wedges if desired.