Preheat your Traeger to 375F.
Start by combining the ingredients for the au jus in a small pan and place it over medium heat: 12 ounces of beef stock, 2 teaspoons of Worcestershire sauce, 1 teaspoon of garlic powder, ½ teaspoon of black pepper.
Soften 5 tablespoons of butter in the microwave and add 2 teaspoons of italian seasoning and ½ of a teaspoon of garlic powder.
Using a serrated knife, cut through the center of the sandwich rolls. Remove the top and set aside.
Brush a thin layer of butter on both sides of the rolls.
Remove the au jus from the stove, to dip the roast beef and layer the slices on the bottom later of the rolls.
Next, layer the slices of provolone cheese and place the top buns back on the cheese.
Brush the top of the rolls with the seasoned butter mixture. Transfer the rolls to your baking sheet or aluminum tray.
Place in the Traeger and close the lid. Cook for 15-20 minutes or until the cheese is gooey and melted.
Remove the sandwiches from the heat and cut through the sliders to serve.