Preheat your oven to 375°F and line a baking sheet with parchment paper.
In a medium bowl, combine the shredded chicken with Buffalo sauce and melted butter, tossing until evenly coated.
Split the hoagie rolls and place them on the prepared baking sheet, cut side up.
Divide the Buffalo chicken mixture evenly among the bottom halves of the rolls, then top each with shredded mozzarella cheese.
Bake for 10-12 minutes until the cheese is melted and bubbly and the bread is lightly toasted.
Remove from oven and drizzle with blue cheese or ranch dressing, then top with shredded lettuce and celery if using.
Place the top buns on and serve immediately while hot and melty!