Preheat the oven to broil and line a baking sheet with parchment paper.
Lightly spread butter across the cut inner surfaces of the hoagie rolls and place them cut-side up on the prepared baking sheet.
Broil the rolls 1 minute or until the inner surfaces are lightly browned and slightly crisp, then remove and reduce oven temperature to 350°F.
In a skillet over medium heat, melt remaining butter and add the cream cheese pieces; stir until cream cheese begins to soften.
Add the shredded chicken and chicken stock to the skillet and stir to combine, then reduce heat to low.
Stir in the Frank's Buffalo hot sauce and shredded sharp cheddar; continue stirring until the cheddar and cream cheese are melted and the mixture is creamy, about 1–2 minutes.
If desired, spread mayonnaise on the toasted buns.
Spoon the hot chicken mixture onto the toasted hoagie rolls, top with provolone if using, then place under the oven (350°F) for 1–2 minutes until the provolone melts.
Remove sandwiches from the oven and sprinkle with blue cheese crumbles and a little extra hot sauce if desired, then serve immediately.
