My absolute favorite sliders! French Onion Roast Beef Sliders are the ultimate party food and always a crowd-pleaser. Hawaiian sweet rolls are topped with deli roast beef, provolone cheese, caramelized onions, and my secret ingredient French onion sour cream, adding so much flavor!! Brush with garlic butter, bake until warm and melty, and serve with an easy homemade au jus!
Melt 3 tablespoons butter in a skillet over medium heat. Add the onions and sprinkle with sugar. Cover and cook until caramelized, stirring occasionally about 15-20 minutes. Turn down the heat if the onions start to burn.
Meanwhile, cut the buns in half lengthwise, leaving them all attached, and place onto a parchment-lined baking sheet. Spread the bottom buns with French onion sour cream, then top with roast beef, cheese, and caramelized onions. Cover with the top buns.
Melt 2 tablespoons butter and mix with garlic and parsley. Brush or drizzle over the top buns.
Bake for 10-15 minutes or until the cheese is melted. If the buns are browning too fast, loosely cover them with aluminum foil.
Meanwhile, make the au jus. Add all the ingredients to a small pot and simmer on low for 10 minutes.