Preheat your oven to 180°C (350°F). Slice the slider buns horizontally, keeping the top attached to the bottom. Set aside.
Warm the BBQ sauce in a small saucepan over medium heat until it begins to bubble and releases a smoky aroma, about 3-5 minutes. Stir occasionally.
Pull apart the ham slices into thinner, manageable pieces, ensuring they're evenly sliced for uniform heating.
Place the bottom half of the buns in a baking dish, then spread a generous layer of the warmed BBQ sauce over them, covering evenly.
Arrange the sliced ham evenly over the sauced buns, then drizzle a little more BBQ sauce on top of the ham for extra flavor and moisture.
If using cheese, sprinkle the shredded cheddar evenly over the ham slices, then carefully place the top half of the buns over everything.
Brush the tops of the buns with the melted butter mixture to add shine and flavor, ensuring an even coating.
Cover the baking dish with foil and bake for 15 minutes, or until the sliders are heated through and the cheese (if used) is melted and bubbly.
Remove the foil and bake uncovered for an additional 3-5 minutes, until the tops are golden brown and caramelized.
Let the sliders rest for 5 minutes, then slice into individual portions if desired. Serve warm with extra BBQ sauce on the side.