Preheat the oven to 350°F. Lightly grease a 9-by-13-inch baking dish.
Add the cooked chicken, barbecue sauce, ranch dressing, dry ranch seasoning, smoked paprika, garlic powder, and black pepper to a large mixing bowl.
Stir until the chicken is evenly coated. The filling should be moist, but there should not be sauce pooled at the bottom of the bowl.
Keep the Hawaiian rolls connected. Use a serrated knife to slice horizontally through the entire slab, creating one connected top half and one connected bottom half.
Place the bottom half of the rolls inside the prepared baking dish.
Sprinkle half of the sharp cheddar and Monterey Jack evenly over the bottom rolls. This cheese layer helps protect the bread from the moist filling.
Spread the BBQ chicken mixture evenly over the cheese.
Top the chicken with the crumbled bacon, diced red onion, and drained pickle slices.
Sprinkle the remaining sharp cheddar and Monterey Jack evenly over the filling.
Place the connected top half of the rolls over the cheese.
Add the melted butter, garlic powder, onion powder, dried parsley, Worcestershire sauce, and optional sesame seeds to a small bowl. Stir until combined.
Brush the garlic-butter mixture generously over the tops and exposed edges of the rolls. Allow some of the butter to settle into the seams between the sliders.
Cover the baking dish loosely with aluminum foil.
Bake at 350°F for 15 minutes.
Remove the foil and bake for another 5 to 8 minutes, or until the tops are golden brown and the cheese is completely melted.
Insert an instant-read thermometer into the chicken filling in one of the center sliders. The filling should reach 165°F.
Remove the baking dish from the oven and let the sliders rest for 5 minutes.
Slice or pull the sliders apart and serve with additional barbecue sauce, ranch dressing, pickles, or jalapeños.