Preheat oven to 375°F.
Line a quarter sheet pan with non-stick aluminum foil.
Place the bottom of the slider buns on the foil-lined pan.
Place five slices of provolone cheese on top of the slider buns, cutting one piece in half and placing the halves in the middle to cover the buns completely.
Place the sliced Leftover Standing Rib Roast or deli-sliced roast beef in an even layer on top of the cheese. Place the remaining five slices of provolone cheese on top of the meat, cutting one slice in half and placing the halves in the middle to cover the buns completely.
Place the tops of the buns on top of the top layer of cheese.
In a microwave-proof bowl, melt the unsalted butter in the microwave for 30 seconds, or until melted.
Add the the garlic powder and Worcestershire sauce to the melted butter and whisk to combine them.
Then, using a basting brush, brush the butter mixture over the tops and sides of the finished sliders.
Bake in a 375°F oven for 12 minutes, or until the case is melted and the meat is thoroughly heated.
Remove from the oven and serve warm.
Yield 12 sliders.