Preheat your oven to 350°F.
In a large skillet over medium heat, combine the beef broth and Worcestershire sauce. Bring to a simmer, then add the sliced roast beef. Cook for about 3-5 minutes until heated through. Season with salt and pepper to taste.
While the beef is heating, place the slider buns on a baking sheet. If desired, slice the buns in half and lay the bottom halves on the sheet.
Layer the provolone cheese over the bottom halves of the buns. Once the beef is heated, evenly distribute the beef over the cheese. Place the top halves of the buns on the beef.
In a small bowl, mix the melted butter, garlic powder, and onion powder. Brush this mixture over the top of the slider buns.
Cover the sliders with aluminum foil and bake in the preheated oven for 15 minutes. Remove the foil and bake for an additional 5-10 minutes, or until the cheese is melted and the tops are golden brown.
Remove from the oven and let cool for a few minutes. Slice the sliders and serve warm with a small bowl of the beef broth for dipping. Garnish with fresh parsley if desired.