Prepare the Horseradish Spread : In a small bowl, mix mayonnaise, cream-style horseradish, and minced garlic until smooth. Refrigerate until ready to use.

Make the Au Jus : In a medium saucepan, melt 2 tablespoons of butter over medium heat. Add diced onions and sauté until softened. Stir in flour and cook for 1-2 minutes to form a roux. Gradually whisk in beef broth and Worcestershire sauce, ensuring no lumps form. Add Better Than Bouillon beef base and bring the mixture to a simmer, stirring until thickened slightly. Season with salt and pepper to taste. Keep warm for serving.

Assemble the Sliders : Preheat oven to 350°F (175°C). Slice the Hawaiian rolls in half horizontally, keeping the bottom and top halves intact. Place the bottom halves in a baking dish Spread the horseradish mixture evenly on the cut side of the bottom rolls. Layer the roast beef and cheese slices over the horseradish spread. Place the top halves of the rolls over the filling.

Brush with Butter Mixture : In a small bowl, combine the melted butter, garlic powder, onion powder, fresh thyme, parsley, and a pinch of salt and pepper. Generously brush the butter mixture over the tops of the rolls.

Bake the Sliders : Cover the baking dish with aluminum foil and bake for 15 minutes. Remove the foil and bake for an additional 5-7 minutes, or until the tops are golden brown and the cheese is melted.

Serve with Au Jus : Cut the sliders apart and serve warm with the prepared au jus for dipping.