If you love French onion soup and cheeseburgers, these sliders are your perfect mash-up. They’re rich, flavorful, and easy enough for a casual weeknight dinner but impressive enough to serve guests. Make a batch for game day, holidays, or anytime you want something cozy and satisfying—no forks required.
If you’ve made my French onion chicken thighs, then you already know how much I love those rich, savory flavors. It was only a matter of time before they made their way into something handheld. These French onion Sliders are juicy, cheesy, and topped with caramelized onions—all tucked into soft, toasted buns.
They’re the kind of recipe we find ourselves coming back to, especially when we want something that feels comforting but a little special. Think of them as a homemade take on a gastropub classic.
They’re just as welcome on a quiet night at home as they are on a party platter. The flavors are bold, the prep is simple, and they always seem to disappear faster than expected.
Reasons to Love This Recipe
Ingredient Overview
Be sure to check out the full recipe and ingredient list below
Here’s a quick look at the key ingredients that bring these sliders to life. Nothing fancy—just flavorful, straightforward components that come together beautifully.
- Yellow Onions. The foundation of that rich, caramelized flavor. Go with yellow onions for the best balance of sweetness and depth. White onions can work in a pinch, but avoid red. They’ll skew the flavor.
- Unsalted Butter + Olive Oil. This combo helps the onions cook evenly without burning. Butter adds richness while the olive oil prevents scorching.
- Fresh Thyme. Adds a subtle earthy note that complements the onions. If you don’t have fresh on hand, dried thyme works too—just use half the amount.
- Balsamic Vinegar. A splash at the end of caramelizing brightens and deepens the flavor. You could use a bit of red wine vinegar in a pinch, but the balsamic’s touch of sweetness is ideal here.
- Beef Broth. Beef broth adds that classic French onion soup flavor and helps deglaze the pan. Go with low-sodium to keep the salt in check.
- Ground Beef (80/20). The ideal fat ratio for juicy patties. You can swap in ground turkey or chicken if you prefer a lighter version, just expect a milder flavor and reduce cooking time slightly.
- Worcestershire Sauce. Adds a subtle tang to the beef. It’s a small addition that makes a noticeable difference.
- Gruyère Cheese. Melts beautifully and brings that French onion soup flavor. Swiss is a reliable alternative if Gruyère isn’t available. It’s milder but still works well. Gruyère is the classic choice, but we actually used Swiss in ours because it’s a more budget-friendly option.
- Slider Buns. Soft, slightly sweet buns like brioche or Hawaiian rolls work best. Potato rolls or any small dinner roll can also do the job.
- Mayonnaise & Dijon Mustard (Optional). A layer of mayo and mustard gives the sliders a creamy, tangy contrast to all the richness. Totally optional, but highly recommended if you enjoy that kind of flavor balance. We keep it simple and usually use just the caramelized onions in ours.
- Fresh Parsley. Adds a bright, fresh finish. You can skip it if you don’t have any on hand. It’s more of a garnish than a must-have.
Make-Ahead and Scaling Tips
- Caramelized onions can be made ahead. This step takes the longest, so it’s worth doing in advance. Cook the onions fully, let them cool, and store them in an airtight container in the fridge for up to 3 days. Reheat gently in a skillet or the microwave before assembling your sliders.
- Need more than six sliders? The recipe is easy to double—or even triple—for parties or game day. Simply double each ingredient and cook the patties in batches. You can keep them warm in a low oven (around 200 F (93 C)) until everything is ready to assemble.
- Serving tip for a crowd. Arrange the bottom buns on a sheet pan, add the patties and toppings, then pop them under the broiler briefly to re-melt the cheese before topping with the buns. It’s a great way to serve everything hot at once without stress.
Step-by-Step Instructions with Photos
This is a brief overview. Be sure to check out the full recipe and ingredient list below
Tips for Success
- Take your time with the onions. This isn’t the step to rush. Low and slow is key to getting that deep golden color and rich flavor. Cranking the heat too high will brown the outside before the inside softens.
- Use a mix of butter and oil. The butter gives you that classic French onion richness, and the oil keeps it from burning while the onions cook down.
- Don’t overmix the beef. A gentle hand goes a long way when forming patties. Overworking the meat can lead to a tough, dense texture.
- Make the patties slightly wider than the buns. Burgers shrink a bit as they cook, so shaping them just a little larger keeps them slider-perfect after grilling.
- Cover the pan to melt the cheese. Trapping the heat helps the cheese melt evenly and quickly. A lid, foil, or even an inverted baking sheet will do the job.
- Toast the buns (if you have time). It’s optional, but toasting adds structure and prevents sogginess, especially helpful if you’re serving these at a party or prepping in advance.
- Prep the onions ahead. As mentioned above, you can make the caramelized onions up to 3 days in advance and store them in the fridge. They reheat beautifully and save you time when assembling.
Storage and Reheating
- Storing Leftovers. Store the cooked beef patties and caramelized onions separately from the buns if possible. Place them in airtight containers and refrigerate for up to 3 days. Assemble sliders just before serving to keep the buns from getting soggy.
- Reheating. For the best results, reheat the patties and onions in a skillet over medium heat until warmed through. You can also microwave them in short bursts, but the skillet helps revive the texture and keeps the cheese gooey. Toast fresh buns if you’re rebuilding the sliders.
- Freezing. The cooked patties freeze well. Let them cool completely, then wrap tightly and freeze for up to 2 months. Thaw overnight in the fridge and reheat in a skillet or a 350 F (177 C) oven until heated through. The onions can be frozen, too, but the texture may soften further once thawed.
more
Gastropub-Inspired Favorites
For the Caramelized Onions:
- 2 tablespoons unsalted butter
- 2 tablespoons olive oil
- 2 large yellow onions thinly sliced
- ½ teaspoon kosher salt
- ½ teaspoon black pepper
- 1 teaspoon fresh thyme leaves or ½ teaspoon dried
- 1 teaspoon balsamic vinegar
- ½ cup beef broth (Note 1)
For the Beef Patties:
- 1 pound ground beef 80/20 blend recommended (Note 2)
- 1 teaspoon Worcestershire sauce
- ½ teaspoon kosher salt
- ½ teaspoon black pepper
- ½ teaspoon garlic powder
- ½ teaspoon onion powder
- 6 slider buns (Note 3)
For the Topping:
- 6 slices Gruyère cheese or Swiss (Note 4)
- 2 tablespoons mayonnaise optional (Note 5)
- 2 tablespoons Dijon mustard optional (Note 5)
- 2 tablespoons chopped fresh parsley for garnish
-
In a large skillet, heat 2 tablespoons unsalted butter and 2 tablespoons olive oil over medium to medium-low heat.
-
Add sliced onions, ½ teaspoon kosher salt, and ½ teaspoon black pepper. Cook, stirring occasionally, until deeply golden and soft, about 25–30 minutes. Don’t rush. This step builds the flavor (Note 6).
2 large yellow onions
-
Stir in 1 teaspoon fresh thyme leaves and 1 teaspoon balsamic vinegar. Cook 1 more minute.
-
Add ½ cup beef broth and simmer for 5 minutes, until the liquid reduces and lightly coats the onions. Remove from heat (Note 1).
-
In a bowl, gently combine 1 pound ground beef, 1 teaspoon Worcestershire sauce, ½ teaspoon kosher salt, ½ teaspoon black pepper, ½ teaspoon garlic powder, and ½ teaspoon onion powder.
-
Divide into 6 equal portions and form into 2½–3 inch patties, just slightly wider than your buns (Note 7).
-
Heat a skillet or grill over medium-high. Cook patties for 3–4 minutes per side or to desired doneness.
-
In the last minute, top each with a slice of Gruyère and cover the pan to melt the cheese (Note 8).
6 slices Gruyère cheese
-
If desired, lightly toast slider buns for added flavor and structure (Note 3).Spread mayonnaise and Dijon mustard on the bottom buns, if using (Note 5).Add the cheesy patties, top with caramelized onions, and sprinkle with parsley.Add top buns and serve warm.
- Use low-sodium beef broth to avoid over-salting. The broth should reduce and lightly coat the onions without being watery.
- An 80/20 beef blend balances flavor and moisture. Avoid overmixing to keep the patties tender.
- Soft slider buns like brioche or potato rolls work best. Toasting helps prevent sogginess and adds a subtle crunch.
- Gruyère melts beautifully and brings a classic French onion soup flavor. Swiss is a good budget-friendly alternative.
- Mayo and mustard are optional but add creamy contrast and tang to the savory filling.
- Caramelizing onions takes time. Keep heat moderate and stir occasionally. Onions should be deep golden and jammy by the end.
- Shaping patties slightly larger than the buns accounts for shrinkage during cooking.
- To melt cheese evenly, cover the pan with a lid, a sheet of foil, or an inverted baking sheet.
- The onions can be made up to 3 days ahead and stored in an airtight container in the fridge. Reheat gently before serving.
- Freezer Tip: Cooked patties freeze well for up to 2 months. Reheat in a skillet or oven.
Calories: 490kcal | Carbohydrates: 21g | Protein: 25g | Fat: 34g | Saturated Fat: 14g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 14g | Trans Fat: 1g | Cholesterol: 95mg | Sodium: 728mg | Potassium: 312mg | Fiber: 2g | Sugar: 4g | Vitamin A: 401IU | Vitamin C: 3mg | Calcium: 337mg | Iron: 3mg
Servings: 6 sliders
Calories: 490kcal
Source link
