Heat the oven. Preheat to 350°F (175°C). Line a 9x13-inch baking dish with parchment or lightly grease it.
Prep the rolls. Without separating the individual rolls, slice the whole slab horizontally so you have a top and bottom. Place the bottom half in the baking dish.
Toss the chicken. In a bowl, mix shredded chicken with 1/2 cup ranch dressing.
Add black pepper and garlic powder. Taste and adjust seasoning.
Layer the cheese. Place half the cheese on the bottom rolls to create a melty barrier that keeps the bread from getting soggy.
Add chicken and bacon. Spread the ranch chicken evenly. Sprinkle the crumbled bacon over the top so every bite gets some crunch and smokiness.
Top with more cheese. Finish with the remaining cheese slices.
Set the roll tops in place.
Make the buttery glaze. Stir melted butter, dry ranch seasoning, and Dijon until smooth. Brush it generously over the tops of the rolls. Don’t skip this step—it adds flavor and a golden finish.
Cover and bake. Tent the dish loosely with foil and bake for 12–15 minutes, until the cheese is melty. Remove the foil and bake another 5–7 minutes to toast the tops.
Garnish and slice. Let the sliders rest 5 minutes.
Sprinkle with fresh chives or parsley, then cut along the roll lines and serve warm. Add extra ranch on the side for dipping if you like.