In a large skillet over medium heat, melt the cream cheese until smooth.
Stir in the dry ranch seasoning, onion powder, and black pepper.
Add shredded rotisserie chicken and chopped green onions to the skillet and stir to combine.
Add 1 cup of shredded cheddar cheese to the chicken mixture and stir until melted.
Preheat oven to 375°F and spray a 9x13-inch baking dish with cooking spray.
Slice each Hawaiian slider roll in half while leaving a hinge to open like a book.
Arrange the slider buns in the baking dish in neat rows.
Fill each bun evenly with the creamy chicken filling and sprinkle with remaining shredded cheddar cheese.
Close the sliders and brush the tops with melted butter mixed with Italian herb blend.
Sprinkle grated parmesan cheese over the buttered tops.
Loosely cover the sliders with foil to prevent over-browning and bake for 15 minutes.
Remove foil and bake for an additional 5 to 10 minutes until tops are golden and filling is hot.
Serve sliders immediately while warm.