French Onion Beef Sliders For A Crowd

Name: French Onion Beef Sliders For A Crowd
Prep time: 20 min
Cook time: 1 h
Total time: 1 h 20 min
Cuisine: American
Ingredients: 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