Step 1

Squeeze excess moisture from horseradish via a fine-mesh sieve or using a clean tea towel. This helps prevent your mayo from being watered down.

Step 2

In a bowl, whisk together the mayonnaise, prepared horseradish, black pepper and salt together until well combined. Set aside.Note: Add a tablespoon or so of horseradish at a time until you've reached your desired flavour.

Step 3

Preheat oven to 350 degrees Fahrenheit.

Step 4

Carefully cut buns in a half horizontally (so you have a bottom portion and top portion and leaving individual buns intact). Note: This recipe makes about 18 to 24 sliders (depending on how much toppings you want on them). Also, if you pile on less (or more) toppings onto your buns, the quantity you yield may vary. You can easily half the recipe if you like.

Step 5

Spread horseradish mayo over the cut sides of the top and bottom buns. Place bottom buns (cut side up) in a baking dish large enough to hold the buns (use two baking dishes if needed, one for each set of 12 buns).

Step 6

Distribute cooked roast beef over buns. Top with caramelized onions and cheese. Then place top buns over top (cut side down). Brush with melted garlic butter.

Step 7

Cover with aluminum foil and bake in preheated oven for 15 minutes. Carefully remove aluminum foil and bake for another 5 minutes or until the cheese is melted and the sliders are heated through.

Step 8

Cut out the individual sliders, serve and enjoy!