12 slider buns, halved
1 large onion, thinly sliced
6 sprigs thyme
kosher salt
Freshly ground black pepper
1 lb. deli roast beef
12 slices provolone cheese
1/4 tsp. garlic powder
2 tbsp. unsalted butter, melted
coarse sea salt
1 tbsp. finely chopped parsley
Au Jus
1 tbsp. unsalted butter
1 Garlic clove, minced
1 1/2 c. beef stock
1 tbsp. Worcestershire sauce
1/4 tsp. thyme leaves
Preheat oven to 350 degrees F. Place bottom halves of the slider buns in a 9 x 13 baking sheet. Melt butter in a large skillet over medium-high heat. Stir in onion and thyme sprigs. Cook, stirring occasionally, until the onions begin to soften and turn slightly golden. Season with salt and pepper and reduce heat to medium. Continue cooking, stirring occasionally, until the onions are soft and caramelized. Remove from heat and pull out thyme sprigs. Top the slider buns with roast beef and cheese, then cover with caramelized onions. Place the remaining halves of the slider buns on top. Brush the tops of the slider buns with melted butter. Sprinkle with garlic powder, sea salt and parsley. Bake until the cheese is melted and the sandwiches are warmed through, about 10 to 15 minutes. Meanwhile, make quick Au jus. Melt butter in a medium skillet over medium heat. Stir in garlic and cook until fragrant. Add beef stock, Worcestershire sauce and thyme. Season with salt and pepper. Simmer for 10 minutes until reduced slightly. Serve sliders warm with Au jus for dipping.