In a small bowl, stir together the melted butter, Dijon mustard, brown sugar, bagel seasoning, and Worcestershire sauce until well-combined.
¼ cup butter , 1 tablespoon Dijon mustard, 2 teaspoons brown sugar, 1 teaspoon everything bagel seasoning, ½ teaspoon Worcestershire sauce
Brush the tops of the rolls with the butter mixture.
Cover with aluminum foil.
Bake for about 15-20 minutes, or until the sliders are heated through and the cheese has melted.
Remove the foil and continue baking for about 5 minutes. Serve warm.
Notes
Roast beef: I use deli sliced roast beef. If you have leftover sliced roast beef, you could use that instead.
Cheddar cheese: I like to use sharp cheddar because it has more flavor. Mild cheddar or medium cheddar would also work. Or feel free to use another type of cheese that melts well, like Havarti or Swiss.
Butter: I use salted butter. Unsalted butter would also work, but I recommend adding a pinch or two of salt for better flavor.
Dijon mustard: The Dijon mustard gives the sauce a nice bite. Yellow mustard or brown mustard are milder alternatives.
Brown sugar: Feel free to adjust the amount of sugar to your liking. The sugar just gives the topping a nice bit of sweetness and balance.
Everything bagel seasoning: The seasoning adds a bit of salty, savory flavor. You could use poppy seeds, sesame seeds, or whatever seasoning you prefer.