Preheat your oven to 350°F (175°C) and lightly grease a 9x13 inch baking dish.
Without separating the individual rolls, slice the entire slab horizontally to create a top half and a bottom half.
Place the bottom half of the rolls in the prepared baking dish. Bake for 4-5 minutes to lightly toast the surface; this creates a barrier that prevents the bottom from becoming soggy once the sauce is added.
In a large mixing bowl, combine the shredded rotisserie chicken, buffalo wing sauce, ranch dressing, and diced celery. Mix until the chicken is evenly coated.
Sprinkle 1 cup of the cheese (a mix of Monterey Jack and cheddar) evenly over the pre-toasted bottom rolls.
Spread the buffalo chicken mixture in an even layer over the cheese.
Top the chicken with the remaining 1 cup of cheese to act as the 'glue' for the top buns.
Place the top half of the rolls over the chicken and cheese layer.
In a small bowl, whisk together the melted butter, garlic powder, and dried parsley. Brush the mixture generously over the tops of the rolls.
Cover the baking dish tightly with aluminum foil. Bake for 10 minutes to melt the cheese.
Remove the foil and bake for an additional 5-8 minutes, or until the tops of the rolls are golden brown and slightly crisp.
Let the sliders rest for 3 minutes before using a sharp knife to slice through the individual rolls. Serve warm.