In a large bowl, combine the shredded chicken, Caesar dressing, grated Parmesan cheese, chopped romaine lettuce, black pepper, and garlic powder. Mix well until all ingredients are evenly coated.
Slice each croissant in half horizontally to create a top and bottom.
Generously spoon the chicken Caesar mixture onto the bottom half of each croissant.
Place the top half of the croissant on the sandwich and press down gently.
If desired, sprinkle extra Parmesan cheese on top for garnish.
Serve immediately or wrap in plastic wrap and refrigerate for up to 2 hours before serving.