In a large bowl, combine buttermilk, garlic powder, onion powder, paprika, salt, and black pepper. Add the chicken breasts and ensure they are fully submerged. Cover and refrigerate for at least 1 hour or up to overnight for best flavor.
Preheat your oven to 400°F. Line a baking sheet with parchment paper.
In a shallow dish, mix together flour, breadcrumbs, and 1/4 cup grated Parmesan cheese. Remove the chicken from the buttermilk marinade, allowing excess to drip off, and dredge each piece in the flour mixture, pressing lightly to adhere.
Place the coated chicken on the prepared baking sheet. Bake for 20-25 minutes, or until the chicken is golden brown and cooked through (internal temperature should reach 165°F).
While the chicken is baking, prepare the sandwich rolls by toasting them lightly if desired.
Once the chicken is done, assemble the sandwiches by placing a piece of chicken on each roll, topping with chopped romaine lettuce, a generous drizzle of Caesar dressing, and additional Parmesan cheese if desired.
Serve immediately and enjoy your crispy chicken Caesar sandwiches!