Turn leftover roast beef into irresistible sliders with melty cheese, caramelized onions, and zesty horseradish mayo. Perfect for busy weeknights or game day!

The Best Way to Use Leftovers – Easy Roast Beef Sliders Everyone Will Love

If you have leftover roast beef in the fridge, this is the best way to turn it into something new and exciting! These Leftover Roast Beef Sliders are layered with tender roast beef, melty cheese, and caramelized onions on soft, sweet Hawaiian rolls. Brush a savory Worcestershire sauce butter mixture on top and spread with a creamy horseradish mayo—every bite is packed with flavor!

This easy dinner recipe is perfect for a busy weeknight, football season, or a fun game-day party. The melted Swiss cheese makes them extra gooey, and their small size makes them great for sharing. Whether you’re feeding a hungry family or putting together a casual dinner with friends, these sliders are always a huge hit.

The best part? They’re quick to put together and disappear even faster. These easy roast beef sliders are guaranteed to be one of your new favorite ways to use up leftovers!

Why you’ll love making Leftover Roast Beef Sliders:

🥪 Quick and easy recipe using leftover or deli roast beef—perfect for busy weeknights or casual family dinners.
🧀 Layered with melty Swiss cheese, caramelized onions, and creamy horseradish mayo on soft Hawaiian rolls.
🎉 Great for parties, game night, or meal prep—these sliders are always a huge hit and reheat beautifully!

Ingredients for Leftover Roast Beef Sliders

1 tbsp olive oil – Used to sauté the onions until they’re soft and caramelized, adding rich flavor.
1 yellow onion, sliced – Caramelized onions bring a touch of sweetness and depth to every bite.
12 Hawaiian rolls – Soft and slightly sweet rolls that are the perfect base for these sliders.
2 tbsp creamy horseradish sauce – Adds a zesty kick that pairs perfectly with roast beef.
1/4 cup mayonnaise – Mixed with the horseradish for a smooth, tangy slider spread.
Leftover roast beef – The star of the show—use chopped pieces of tender, juicy roast beef from a previous meal.
6 slices Swiss cheese – Melts beautifully over the beef, giving that gooey, savory finish.
3 tbsp butter, melted – Brushed over the tops of the rolls to help them bake up golden and flavorful.
1/2 tbsp Dijon mustard – Mixed with the butter topping for a subtle tang and added depth.
1/2 tsp garlic powder – Adds a hint of savory, garlicky flavor to the butter topping.
1/2 tsp onion powder – Boosts the onion flavor and pairs well with the caramelized onions.
1 tbsp Worcestershire sauce – Mixed into the butter topping—it gives that umami boost that brings everything together.
1 packet Au Jus Mix (optional) – Mix up this sauce to serve as French Dip Roast Beef Sliders.

Assembling Your Roast Beef Sliders

Preheat your oven to 375°F and lightly spray a 9×13-inch baking dish with nonstick cooking spray.
In a skillet over medium-high heat, add the olive oil and sliced yellow onions. Cook, stirring occasionally, until the onions are soft and golden brown. Set aside.

Without separating the rolls, slice them in half horizontally to create a top and bottom layer. Keep each layer intact.
In a small bowl, mix the creamy horseradish sauce and mayonnaise. Spread the mayo mixture on the cut sides of both the top and bottom layers of the rolls.

Place the bottom half of the rolls into the prepared baking dish. Lay the slices of Swiss cheese over the rolls.
Warm up the leftover roast beef on the stovetop or in the microwave. Chop or shred it into bite-sized pieces, then spread it evenly over the cheese layer.
Add the caramelized onions on top of the roast beef.

Replace the top buns over the onion layer to complete the sliders.
Melt the butter in a microwave-safe measuring cup or bowl. Stir in the Worcestershire sauce, Dijon mustard, garlic powder, and onion powder until well combined.
Brush the melted butter mixture generously over the top of the rolls.
If you’d like, sprinkle poppy seeds or sesame seeds on top for extra flavor and crunch.
Bake the sliders for 15-20 minutes, or until the tops are golden brown and the cheese is melted.
Carefully remove from the oven and let the sliders rest for about 5 minutes on a cutting board.
Slice into individual portions using a serrated knife and serve warm.

Recipe Variations & Serving Suggestions

Use deli roast beef if you don’t have leftovers on hand. Just ask for it to be sliced thin at the deli counter—it works great in a pinch!
Swap the cheese to change up the flavor. Try cheddar cheese for a sharper bite, or go with slices of provolone cheese for a smooth, mild taste.
Make French dip sliders by serving them with a side of au jus for dipping—just like a mini version of a classic French dip sandwich!
Add sautéed mushrooms or bell peppers for extra texture and flavor. These pair especially well with provolone or Swiss.
Try different types of cheese, such as mozzarella, pepper jack, or even smoky gouda, to match your mood or the season.
Serve with a side salad, chips, or fries to make it a complete and easy weeknight dinner.
Perfect for parties or game day, keep them warm in a slow cooker on the “warm” setting and let guests help themselves.

Storage and Reheating Tips

These Leftover Roast Beef Sliders are just as tasty the next day—perfect for quick lunches or a second round of easy dinners!

To Store:

Let the sliders cool completely before storing.
Place leftovers in an airtight container or wrap them tightly with foil or plastic wrap.
Store in the refrigerator for up to 3–4 days.

To Reheat:

For best results, reheat in the oven at 350°F for about 10–12 minutes, or until warmed through and the cheese is melty again.
You can also reheat individual sliders in the microwave for about 30–45 seconds, but the rolls may be softer instead of toasty.

Want to keep the buns from getting soggy? Store the sliders in a single layer and reheat uncovered for the best texture!

Turn Leftovers Into Something Delicious

These delicious sliders are the perfect way to turn leftovers into something your whole crew will rave about. With warm layers of roast beef, melty cheese, and a golden buttery topping, they’re one of our new favorite things to make for busy weeknights, game night, or even as easy party food. Whether you’re serving them up for a casual family dinner or feeding a crowd, these sliders always hit the spot. Next time you’ve got extra roast beef, you’ll know exactly what main dish to make!

Pin for later!