Marinate the Chicken: In a bowl, whisk together buttermilk, salt, and hot sauce. Add the chicken thighs and make sure they’re fully coated. Cover and refrigerate overnight (or at least 8 hours).
Prep the Coating: In a shallow bowl, mix flour, cornstarch, garlic powder, paprika, and black pepper.
Remove chicken from the marinade, letting excess drip off. Dredge in the flour mixture, pressing firmly to create craggly edges for maximum crunch. Let sit for 5–10 minutes so the coating adheres.
Fry the Chicken Heat 1–2 inches of neutral oil in a skillet or heavy-bottomed pot to 350°F.Fry the chicken for 5–7 minutes per side, until deeply golden and cooked through (internal temp should reach 165°F). Transfer to a wire rack and immediately sprinkle with a pinch of salt. Toast the Rolls: Lightly toast the sesame hoagie rolls until warm and slightly crisp on the edges.
Build the Sandwich Spread a generous layer of Caesar dressing on both sides of the rolls. Alternatively, you could toss the romaine in the dressing and add to the sandwich. Add the crispy fried chicken, then pile on shredded romaine. Finish with freshly grated parmesan.