French Onion Roast Beef Sliders

Preheat your oven to 350 degrees Fahrenheit.
Spray the bottom of a 9x13'' pan baking dish with cooking spray or line the dish with parchment paper or aluminum foil for easy cleanup.
Remove your Hawaiian rolls from the package, keeping the rolls together.
Use a serrated knife to slice the whole block of rolls in half horizontally and separate the top buns, set aside.
Place the bottom layer of the rolls into your prepared pan.
Lay down your first half of cheese slices across the bottom layer, covering the surface.
Next, pile on the deli-sliced roast beef evenly over the cheese layer.
Sprinkle the French-fried onions evenly all over the beef.
Lay down the remaining slices of cheese evenly across the top of the onion layer, covering the whole surface.
Add the top layer of the rolls.
In a small bowl or or heat-safe dish, melt the butter in the microwave.
Remove one tablespoon of powder from the au jus gravy mix packet.
To the bowl with the melted butter, add the gravy mix, Worcestershire sauce, mustard, garlic powder, and onion powder to the melted butter and stir until combined.
Brush the melted butter mixture all over the top of the rolls.
If using sesame seeds or Everything Bagel seasoning, sprinkle across the top of the rolls.
Place the pan of sliders into the oven uncovered. Bake for 15-20 minutes until golden brown on top.
Once the sliders come out of the oven, garnish with fresh parsley or thyme if desired.
Serve with au jus on the side for dipping if desired (see notes below).