Preheat oven and line sheet:
Heat oven to 350°F (175°C). Cover a baking sheet with parchment paper.Cut rolls horizontally:
Without separating the rolls, cut them horizontally and set the bottom half on the lined sheet. Reserve the tops.Mix chicken with BBQ sauce:
In a bowl, mix the shredded chicken with 1/2 cup BBQ sauce until combined.Assemble sliders with toppings:
Evenly distribute the BBQ chicken over the bottom rolls. Add extra BBQ sauce if desired. Scatter the red onion slices evenly. Top with the shredded cheese. Place the top rolls on the sandwiches.Brush tops with butter:
Spread the melted butter over the roll tops.Bake covered then uncovered:
Cover loosely with foil and bake for 12 minutes. Remove foil and bake another 5 minutes, until the cheese is melted and the buns are golden.Separate sliders before serving:
Separate the sliders using a sharp knife or kitchen shears before serving.