Longhorn’s French onion soup is all about patience—deep brown onions and a cheesy, broiled top bring it all home.
I cook the onions low and slow for nearly 40 minutes, stirring often, until they’re soft and sweet with dark edges.
Don’t rush the broiling—let the cheese bubble and brown across the top for that slightly chewy, golden crust.
I like to use Gruyère mixed with provolone—it melts better and has just the right stretch when you lift your spoon.
I keep the bread thick so it doesn’t disintegrate into the soup before serving. So much yum!
How to Make Longhorn’s French Onion Soup
Ingredients
- 4 large Yellow Onions
- 4 tbsp Butter
- 2 tbsp Olive Oil
- 2 tsp Sugar
- 1 tsp Salt
- 1 tsp Black Pepper
- 2 cloves Garlic
- 8 cups Beef Broth
- 2 Bay Leaves
- 1 tsp Thyme
- 1 French Baguette
- 2 cups Gruyère Cheese (shredded)
- 1 cup Provolone Cheese (shredded)
Step-by-Step Instructions
Step 1:
Slice the onions into thin rings and mince your garlic.
Step 2:
Heat a big pot over medium-low, then toss in butter and olive oil.
Step 3:
Add onions, sugar, salt, and pepper.
Stir now and then for about 35-40 minutes until the onions turn a deep golden brown.
Step 4:
Stir in garlic, thyme, and bay leaves for about a minute so everything gets fragrant.
Step 5:
Pour in beef broth, crank up the heat to bring it to a boil, then drop it down and let it simmer uncovered for 30 minutes.
Step 6:
While that’s simmering, slice your baguette and toast the pieces in the oven until they’re golden and crisp.
Step 7:
Ladle soup into oven-safe bowls, top with a toasted bread slice, and then add Gruyère and Provolone on each.
Step 8:
Broil for 2-3 minutes until the cheese melts and bubbles.
Tips and Tricks for Making This Recipe
Slicing the Onions
Cut the onions thin and as evenly as you can for the best caramelization and texture.
Achieving the Perfect Caramelization
Let the onions brown slowly on medium-low heat.
Try not to rush it—patience brings out all that deep, sweet flavor.
Cheese Choices
Gruyère is classic, but don’t sweat it—Swiss or provolone works if that’s what you have or want to save a few bucks.
Toasting the Bread
Toast the baguette slices until they’re crisp all the way through so they don’t go soggy in the soup.
That way, they soak up broth but still hold up under the cheese.
Taste as You Go
I always taste my soup before serving and tweak the salt or pepper as needed so it’s just right for everyone.
What to Serve with Longhorn French Onion Soup
Green Salad with Tangy Vinaigrette
A crisp green salad is my go-to when you want something light to balance all that savory, cheesy soup.
I like to use mixed greens with a bit of arugula, toss in some cherry tomatoes, maybe a sliced radish, and finish with a punchy vinaigrette.
The acidity really cuts through the richness, making every bite feel a little fresher.
Garlic Butter Baguette
French onion soup and bread—can’t beat that combo, especially with a warm, garlicky baguette.
Dip those crunchy slices right in and let them soak up the broth.
It adds another layer of flavor and texture.
For extra oomph, sprinkle some fresh parsley on top before serving.
Roasted Beet and Citrus Salad
Want a twist? Try a roasted beet and citrus salad on the side—it’s surprisingly good.
Roasted beets with orange or grapefruit segments, a light vinaigrette, and toasted walnuts make for a bright, colorful plate.
The sweet, earthy flavors play well with the soup’s savory notes.
Parmesan Herb Popovers
Popovers aren’t on every table, but I think they’re a fun, airy change from regular bread.
Bake them with Parmesan and a sprinkle of dried herbs for extra flavor.
Serve them hot so you get that cheesy aroma and soft puff.
They’re perfect for tearing and dunking right into your soup.
Miso Roasted Brussels Sprouts
Feeling adventurous? Miso-roasted Brussels sprouts are a wild card but totally worth it.
I toss halved sprouts with white miso, olive oil, and a splash of soy sauce, then roast until the edges get crispy.
The salty-sweet umami is something different and, weirdly enough, makes the soup taste even better.
Variations and Substitutions
Changing the Cheese
Switch out Gruyère for Swiss, provolone, or even mozzarella if you want something milder or just need to use up what’s in the fridge.
For a nuttier flavor, toss a little parmesan into the cheese mix.
Broth Options
You can use chicken or vegetable broth instead of beef if you want it lighter or vegetarian.
I’ve mixed chicken and beef broth before and it still turned out rich and tasty.
Onion Choices
No need to stick to yellow onions.
I like mixing in sweet or red onions for more depth, honestly.
Blending different types can really amp up the flavor, so don’t be afraid to experiment.
Bread Alternatives
Sourdough and baguette are classics, but any sturdy bread will do if you’re short on time.
It just needs to hold up under all that cheese and broth.
How to Store Leftover Longhorn French Onion Soup
Refrigerating the Soup
If you’ve got leftovers, put the soup (without bread and cheese) in an airtight container and pop it in the fridge.
It’ll keep for up to four days.
I usually let it cool a bit before sealing so steam doesn’t build up and make things watery.
Seal it tight to keep it fresh and avoid any weird fridge smells sneaking in.
Freezing for Later
You can freeze this soup—just leave out the bread and cheese.
I like using small mason jars or freezer containers, leaving about an inch at the top for expansion.
Label the date on your containers—it’s easy to lose track of what’s in the freezer, right?
Storing Bread and Cheese
Keep any extra toasted bread and shredded cheese separate in resealable bags or containers.
This way they stay crisp and fresh, so you can just assemble your bowl when you’re ready for leftovers.
Common Mistakes to Avoid
Not Caramelizing Onions Properly
If you rush the onions, you’ll miss out on that deep, sweet flavor that really makes the soup.
Caramelizing takes time—at least 40 minutes on low heat, stirring often.
Don’t crank up the heat to rush it.
Trust me, patience pays off. Skipping this step leaves the soup bland every time.
Using the Wrong Cheese
If you swap in a cheese that doesn’t melt well, you won’t get that classic texture and taste.
Swiss, provolone, or Gruyère are your best bets.
Cheese that won’t melt just turns rubbery or floats on top instead of making that bubbly, golden crust.
I always pile it on—can’t resist that perfect cheesy layer!
Forgetting the Bread
If you forget the bread or just grab some basic sandwich slices, the topping basically falls apart or turns soggy in the soup almost instantly. Not fun.
A sturdy baguette—sliced and toasted—works way better.
It holds together, soaks up all the good stuff, and doesn’t disintegrate on you.
I usually toss my bread under the broiler until it’s crisp, but not rock hard.
Just enough crunch, you know?
Longhorn French Onion Soup Recipe
Ingredients
- 4 large Yellow Onions
- 4 tbsp Butter
- 2 tbsp Olive Oil
- 2 tsp Sugar
- 1 tsp Salt
- 1 tsp Black Pepper
- 2 cloves Garlic
- 8 cups Beef Broth
- 2 Bay Leaves
- 1 tsp Thyme
- 1 French Baguette
- 2 cups Gruyère Cheese shredded
- 1 cup Provolone Cheese shredded
Instructions
- Slice the onions into thin rings and mince your garlic.
- Heat a big pot over medium-low, then toss in butter and olive oil.
- Add onions, sugar, salt, and pepper.
- Stir now and then for about 35-40 minutes until the onions turn a deep golden brown.
- Stir in garlic, thyme, and bay leaves for about a minute so everything gets fragrant.
- Pour in beef broth, crank up the heat to bring it to a boil, then drop it down and let it simmer uncovered for 30 minutes.
- While that’s simmering, slice your baguette and toast the pieces in the oven until they’re golden and crisp.
- Ladle soup into oven-safe bowls, top with a toasted bread slice, and then add Gruyère and Provolone on each.
- Broil for 2-3 minutes until the cheese melts and bubbles.