1. Preheat the oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish or rimmed baking sheet with butter or cooking spray.

2. Without separating the individual rolls, slice the sheet of slider buns in half horizontally, like a big sandwich. Place the bottom half in the prepared pan, cut side up.

3. In a large bowl, combine the shredded cooked chicken and BBQ sauce. Add the smoked paprika or chili powder if using. Stir until all of the chicken is evenly coated and taste to adjust seasoning if needed.

4. Sprinkle half of the shredded cheese evenly over the cut side of the bottom buns.

5. Spoon the BBQ chicken mixture over the cheese, spreading it all the way to the edges so every slider will be well filled.

6. Arrange the sliced red onion evenly over the BBQ chicken.

7. Top with the remaining shredded cheese, covering the chicken and onions in a fairly even layer.

8. Carefully place the top half of the slider buns over the filling, lining up the edges with the bottom buns. Press down very gently so the layers settle without squeezing out the filling.

9. In a small bowl, stir together the melted butter, minced garlic, and a pinch of salt. Brush this garlic butter all over the tops of the buns.

10. Sprinkle the tops with chopped parsley or chives if using.

11. Cover the pan loosely with foil and bake for 10 minutes.

12. Remove the foil and bake for an additional 2–5 minutes, or until the tops are deep golden brown and the cheese is melted and bubbly.

13. Let the sliders rest for about 5 minutes, then use a sharp knife to cut along the lines between the rolls.

14. Serve warm and enjoy, or cool completely before packing leftovers into an airtight container for later.