Description

These French Onion Beef Sliders are a perfect crowd-pleaser featuring caramelized sweet onions, savory ground beef infused with beef base and Worcestershire sauce, topped with melted Gruyere or Swiss cheese on toasted slider buns. Finished with a flavorful butter glaze and a sprinkle of sesame seeds and herbs, these sliders bring a gourmet twist to a classic comfort food ideal for parties and gatherings.

Ingredients

Units Scale

For the Onion Beef Mixture

8 tablespoons (1 stick) butter, divided
2 large sweet onions, sliced
2 pounds ground beef
2 tablespoons beef base (such as Better than Bouillon), divided
1 tablespoon Worcestershire sauce, divided
Kosher salt and black pepper, to taste

For the Sliders

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

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Instructions

Caramelize Onions: Melt 2 tablespoons of butter in a skillet over medium heat. Add the sliced sweet onions and reduce heat to medium-low. Cook, stirring occasionally, until the onions are lightly caramelized and soft, about 25-30 minutes, adding a tablespoon of water if they start to dry or burn.
Prepare Beef Mixture: In a large bowl, combine the ground beef with half the beef base and half the Worcestershire sauce. Season with kosher salt and black pepper to taste and mix well.
Brown Beef with Onions: Add the beef mixture to the skillet with the caramelized onions. Increase heat to medium-high and cook while breaking up the beef, mixing it with the onions until browned. Drain any excess grease from the skillet.
Preheat Oven and Prepare Buns: Preheat your oven to 350°F (175°C). Lightly grease a large baking sheet. Separate the tops from the bottoms of the slider buns, then arrange the bottom buns tightly on the baking sheet.
Assemble Sliders: Evenly spread the onion and beef mixture over the bottom slider buns. Sprinkle shredded Gruyere or Swiss cheese generously over the beef, then cover with the top slider buns.
Make Butter Glaze and Brush Buns: In a microwave-safe bowl, melt the remaining butter with the rest of the beef base. Stir in the remaining Worcestershire sauce until well combined. Using a pastry brush, brush this beefy butter mixture evenly over the top buns. Sprinkle the tops with sesame seeds, fresh thyme, onion powder, and garlic powder.
Bake Sliders: Bake the assembled sliders in the preheated oven for about 20 minutes, or until the cheese has fully melted and the tops of the buns are lightly browned and toasted.

Notes

Use sweet onions such as Vidalia or Walla Walla for best caramelization and sweetness.
For more robust flavor, allow the caramelized onions to caramelize a bit longer but watch carefully to avoid burning.
Beef base can be substituted with beef stock concentrate or beef bouillon cubes dissolved in a small amount of hot water if needed.
Gruyere cheese offers a nutty and creamy texture, but Swiss cheese is a suitable mild alternative.
These sliders can be made ahead and baked just before serving to keep buns fresh and warm.
Optionally, add a slice of caramelized onion or pickles on top before closing buns for extra flavor.