Grease a 9×13 baking dish with the room temperature butter.
Without pulling the rolls apart, slice the rolls in half with a sharp, serrated knife. Place the bun bottoms in the baking dish.
Layer the rolls evenly with the following: 6 slices of provolone cheese, roast beef, French fried onions, 6 more slices of provolone cheese, and the bun tops.
Melt the stick of butter and combine well with 1 tablespoon of the Au Jus seasoning mix, Worchestershire sauce, toasted sesame seeds, dried minced garlic, onion powder, and seasoned salt.
Brush the butter mixture over the bun tops so it’s coated evenly and completely.
Pop into the over for 15-20 minutes, or until the cheese is melted and the bun tops are browned.
While the sliders are cooking, make the dipping sauce: Combine the rest of the Au Jus seasoning packet with 2 cups of cold water. Bring to a boil, then reduce heat to a simmer and allow sauce to thicken.
After the cheese is gooey and the tops are browned, take out of the oven, cut the sliders with a sharp spatula or knife, serve, and enjoy!