8 tablespoons (1 stick) butter, divided
2 large sweet onions, sliced
2 pounds ground beef
2 tablespoons powder beef base, divided
1 tablespoon Worcestershire sauce, divided
1 tsp dried thyme
Kosher salt and black pepper to taste
24 slider buns
12-16 ounces shredded Alpine Chees blend with swiss and gruyere (found at Kroger)
2 tablespoons sesame seeds
1 tablespoon fresh thyme
1 teaspoon onion powder
1 teaspoon garlic powder
Melt 2 tablespoons of the butter in a skillet over medium heat. Add in the onions and reduce the heat to medium low. Cook stirring occasionally, until lightly caramelized, about 25-30 minutes. In a large bowl mix the ground beef with half of the beef base and half of the Worcestershire sauce. Season with salt and pepper and dried thyme. Add the beef to the skillet with the onions. Increase heat to medium-high and brown the beef breaking it up and mixing with the onions as you go. Once browned, drain off excess grease. Preheat oven to 350 degrees. Lightly grease a large baking sheet. Separate the tops from the bottom of the slider buns. Fit the slider bottom buns tightly on the baking sheet. Evenly distribute the beef and onion mixture over the bottom buns. Top with cheese. Cover with the top buns. In a microwave-safe bowl, melt the butter with the remaining beef base. Stir in the remaining Worcestershire sauce and continue to mix until well combined. Using a pastry brush, brush the beefy butter mixture over the top buns. Sprinkle with the sesame seeds, thyme, onion powder and garlic powder. Bake the sliders until the cheese is fully melted and the tops of the rolls are lightly browned, about 20 minutes.