Sauté the onions: Melt 2 tablespoons of unsalted butter, add sliced onion and sauté for 12–15 minutes until soft and caramelized. Add thyme, salt, and pepper, then remove from heat.

Preheat the oven: While the onions cool, preheat your oven to 350°F (175°C).

Prepare the rolls: Keep Hawaiian rolls intact, slice them in half horizontally, and place the bottom halves in a large baking dish.

Layer with cheese and beef: Place half of the provolone cheese slices over the bottom halves, then cover with the sliced deli roast beef.

Add onions and cheese: Spread sautéed onions over the beef, then top with the remaining provolone cheese slices. Place the top halves of the rolls on.

Brush with butter mixture: Mix melted unsalted butter with dried onion soup mix, brush over the assembled sliders.

Bake the sliders: Cover loosely with foil and bake for 25 minutes. Remove foil and bake for an additional 5 minutes.

Prepare the au jus: While baking, prepare au jus using 3 cups water according to package instructions.

Serve warm: Let sliders cool slightly, serve warm with au jus for dipping.