French Onion Beef Sliders For A Crowd

Bahan-bahan (24 porsi)

• 8 tablespoons (1 stick) butter, divided
• 2 large sweet onions, sliced
• 2 pounds ground beef
• 2 tablespoons beef base (such as Better than Boullion), divided
• 1 tablespoon Worcestershire sauce, divided
• Kosher salt and black pepper, to taste
• 24 slider buns
• 12 -16 ounces gruyere or swiss cheese, shredded
• 2 tablespoons sesame seeds
• 1 tablespoon fresh thyme
• 1 teaspoon onion powder
• 1 teaspoon garlic powder