Cheesy Roast Beef Sliders With Caramelized Onions

Name: Cheesy Roast Beef Sliders With Caramelized Onions
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Ingredients: 6 to 8 tablespoons prepared horseradish (squeezed of excess moisture (use less if you want less of a horseradish flavour)); 1 cup mayonnaise; pinch freshly ground black pepper; pinch salt; 18 to 24 mini slider buns (brioche buns are great here); 2 pounds cooked roast beef (shredded or roughly chopped (about 5.5 to 6 cups)); 1 to 1.5 cups caramelized onions (depending on how much onion flavour you want (or you can use fried onions, if you like)); 12 ounces Swiss cheese slices (or 3 cups shredded Swiss cheese); 2 to 3 tablespoons garlic butter (melted)

Published: October 31, 2019 Updated: February 18, 2020 / By: Dawn | Girl Heart Food 29 Comments

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These cheesy roast beef sliders are topped with lots of leftover roast beef, Swiss cheese, caramelized onions and a simple horseradish mayo. Always a hit for both dinner or game day!

Just a little while back, I shared a recipe for caramelized onions. Besides enjoying them straight out of the pan, what did I do with them?

I made a delicious beef slider recipe!! Well, beef sliders with caramelized onions, plenty of ooey gooey cheese and a horseradish mayo. Hungry yet?

Hubby and I started making sliders for Halloween. We usually pick between this roast beef slider recipe or sloppy joe sliders.

Random, right?

I don’t know why we started having sliders for Halloween, but it’s definitely not a bad idea!

And if you’re looking for something to go with these, homemade potato wedges are always a good choice!

What Are Sliders?

Sliders are basically little burgers or sandwiches.

Because they’re little (typically two inches across), if they’re the main course for dinner, then one would typically enjoy a few.

And, forgetting all these technicalities, don’t ya think mini food is the cutest?

How To Make This Beef Slider Recipe

Full details are in the recipe card below, but here are the basics:

Carefully use a knife to cut the buns in half through the middle (so you have a bottom half and top half, leaving individual buns intact). Then spread horseradish mayo over the cut sides of both the bottom portion and top portion of buns. Place the bottom portion into a baking dish, while setting the top potion aside while you start to assemble the sliders.
Distribute roast beef (that has been shredded) and caramelized onions over top of the bottom buns.
Layer on cheese slices.
Place the top buns over the cheese, then brush the buns with a little melted garlic butter.
Cover with aluminum foil and bake (partway through, remove foil).
Once the shredded beef sliders are heated through and the cheese is melted, carefully remove them from the oven, then cut into individual sliders and serve.

Collage of steps to make roast beef sliders with caramelized onions & cheese.

Best Bun To Use for Sliders

Many grocery stores now carry small buns specifically for this purpose.

I picked up brioche buns, but choose whatever variety you like best.

Can’t find slider buns? Use dinner rolls! If there’s too much bread, just cut out some of the centre so you have a thinner top and bottom. Easy!

Can I Use Store Bought Beef Instead?

Absolutely!

Aide from preparing roast beef at home, you can totally use store-bought cooked roast beef instead. Just go to your grocery deli and ask them to cut some off for you! Shaved or sliced deli roast beef works great.

Hand holding a cheesy roast beef slider.

How To Make Horseradish Mayo

All that’s needed for this horseradish mayo is horseradish, mayonnaise and a pinch each of salt and pepper.

Use as little or as much horseradish as you like, depending on your preference.

Tip: Squeeze out any excess moisture from the horseradish so you don’t water down the mayo.

You basically mix the ingredients together in a bowl until combined and use on these sliders.

Not into horseradish mayo? Mix things up! Add either hot sauce, BBQ sauce or Dijon mustard to the mayonnaise instead. Or just have the mayonnaise as is. Either works wonderfully with these pulled beef sliders!

Stack of two roast beef and cheese slider sandwiches.

Tips and Variations

These are beef sliders for a crowd, but you could easily half the recipe if you prefer.
Don’t have garlic butter on hand? Infuse some butter with minced garlic and heat up to get that garlic going. Not a fan of garlic? Use regular butter.
Swiss cheese was used here, but you could use your favourite melty cheese. Cheddar, mozzarella or Gouda would also be delicious options.
Don’t have caramelized onions on hand or don’t have time to make them? Try fried onions instead. They’re quicker to prepare and you’ll still get an onion flavour.
Add some texture! Sprinkle some sesame seeds or poppy seeds onto those buttered buns before baking.
If you have leftover au jus from your roast beef dinner, heat that up and serve alongside so they’re like French dip sliders!

Hand holding a beef slider with cheese after it has been dipped in au jus.

More Cheesy Recipes

If you make this roast beef slider recipe, be sure to leave a comment below!