French Onion Soup
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This French onion soup is deeply savory, rich with caramelized onions, and topped with bubbling, golden Gruyère. With a double-onion method for extra depth and silky texture, it tastes as if it came straight from a cozy Paris bistro.
French onion soup — soupe à l’oignon — has a bit of a reputation, but it’s far more doable than it seems. With butter, plenty of yellow onions, good beef broth, a splash of red wine and dry sherry, Worcestershire sauce for depth, and fresh thyme for warmth, you can build a deeply savory, restaurant-worthy soup right at home.
What truly sets this version apart is that I caramelize the onions in two batches. The first cooks down until it almost melts into the broth, adding body and rich, concentrated flavor. The second batch is caramelized just until silky and golden, giving you those beautiful strands in every spoonful. Finished with olive oil–tossed bread and bubbling Gruyère on top, it’s classic comfort with just a little extra magic.
Bon Appetit: Pro tips for an authentic French onion soup
I grew up loving the French onion soup that a family friend (and accomplished chef) taught me how to make. Here are the tips I learned to make the absolute best French onion soup:
- Low and slow: Caramelize the onions over steady medium heat until golden and jammy — rushing leads to burning, not depth.
- Double the onions: Cook one batch longer so it melts into the broth and adds body, while the second batch keeps those silky strands.
- Use great broth: Homemade beef stock is wonderful, but a quality store-bought (look for bone broth) works beautifully.
- Toast the bread: A lightly toasted baguette holds up under the broth and cheese without turning soggy.
Make it in a slow cooker
This French onion soup recipe can easily be adapted for the slow cooker. There are two ways you can approach this: either use a skillet to caramelize the onions or keep everything in the slow cooker.
- From skillet to slow cooker: To speed things up a bit, start by caramelizing your onions in a large pan. Once they’re done, transfer the caramelized onions to the slow cooker. I would call it a shortcut, but it’ll still take some time!
- Just the slow cooker: If you want to make your French onion soup entirely in the slow cooker, you can! Add the butter, onions, salt, and pepper directly into the slow cooker. Set your slow cooker to low, cover it, and let it cook for 10-12 hours, stirring every few hours if possible.
Once those onions are perfect, finish the recipe by adding flour, wine, sherry, broth, and thyme. Let it cook on low for another 2-3 hours to let those flavors really come together. When you’re ready to serve, ladle the soup into bowls, top with your toasted baguette and Gruyere, and broil until that cheese is all melty and golden.
French Onion Soup Recipe
Ingredients
- 4 tablespoons butter (salted)
- 4 lb yellow onions (peeled and thinly sliced)
- 1 teasoon EACH: sea salt and pepper
- 2 tablesoons all-purpose flour
- 1 cup dry red wine
- 2 tablesoons dry sherry
- 6 cups beef bone broth (see notes)
- 1 tablespoon fresh thyme leaves
- 1 tablespoon Worcestershire sauce (optional – see notes)
The Topping
- 1 baguette (cut into cubes)
- 2 tablespoons olive oil
- 1 teaspoon Italian seasoning
- ¼ teaspoon EACH: salt and pepper
- 1 ½ cups grated gruyere
Instructions
- Melt the butter in a large soup pot over medium heat. Add HALF the sliced onions, the salt and pepper and stir well. Cover the pot and cook the onions for 30 minutes, stirring every 10 minutes. The onions will be wet and simmering in their own liquid. If they look like they're boiling hard, reduce the heat to medium-low.4 tablespoons butter, 4 lb yellow onions, 1 teasoon EACH: sea salt and pepper
- Add the remaining onions to the pot, cover, and cook for 10 minutes. Remove the lid, stir, and continue to cook with the lid off stirring every 5 minutes until the liquid has evaporated and the onions are golden, about 20 minutes more.
- Add the flour to the pot and stir well. Add the wine and sherry and simmer for a few minutes. Add the bone broth, thyme, and if using, Worcestershire sauce, and bring the pot to a simmer. Continue to let it simmer, uncovered, for 10 minutes.2 tablesoons all-purpose flour, 1 cup dry red wine, 2 tablesoons dry sherry, 6 cups beef bone broth, 1 tablespoon fresh thyme leaves, 1 tablespoon Worcestershire sauce
- While the soup is cooking, make the croutons. Preheat your oven to 425 degrees Fahrenheit. Toss the bread cubes, olive oil, Italian seasoning, salt, and pepper in a large bowl until the bread is well-coated. Spread the croutons in a single layer on a baking sheet and toast in the oven for 12-15 minutes. You want them to be toasted but not hard.1 baguette, 2 tablespoons olive oil, 1 teaspoon Italian seasoning, ¼ teaspoon EACH: salt and pepper
- When the soup has finished cooking, ladle it into ovenproof crocks and top with a handful of croutons and some gruyere. Place the crocks on a baking sheet (for easier handling) and broil them for 2-3 minutes, until the cheese has melted. Serve right away.1 ½ cups grated gruyere
Video
Notes
Nutrition
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Recipe FAQs
If you don’t find the answer you’re looking for here, you can ask it in the comments below, and we’ll get back to you as soon as possible!
How to store leftovers?
It’s best to store the French onion soup base without the croutons and cheese on top. Once it’s cooled, transfer it to a covered container and refrigerate for up to 4 days. When reheating, bring it to a simmer on the stove and toast fresh croutons to serve with it.
Can I freeze French onion soup?
You can! Pop it in a freezer-proof container and store it for up to 3 months; however, freeze the soup without the croutons and cheese. Thaw it in the fridge a day before you wish to enjoy it. Reheat the soup on the stove, then add the croutons and cheese fresh, and broil it.
What type of cheese works best for French onion soup?
Gruyère is the classic choice for its nutty flavor and excellent melting properties. However, Swiss cheese, Emmental, or even mozzarella can work in a pinch if Gruyère cheese is unavailable.
Can I make French onion soup with garlic?
You might have noticed garlic cloves were not on the ingredients list. While this might sound like sacrilege to the garlic lovers among us, it’s not a traditional ingredient in a classic French onion soup. If you want, add a clove or two toward the end of the caramelizing process.
This is a delicious soup with tons of flavor! I love the trick for caramelizing the onions! Works perfectly! I topped mine with a cheesy homemade sourdough round. So good!
Aw, I’m so happy you loved it! Those caramelized onions really are the secret — they make such a difference. And topping it with a cheesy homemade sourdough round sounds absolutely incredible. Thank you for sharing your delicious twist! 💛
This is worth the time it takes to make. Savory, hot, gooey comfort is just what I needed on a snowy day. Freeze extra to pop in the freezer for hectic days!
Aw, this is such a lovely note — thank you! I’m so happy it hit the spot on a snowy day. And freezing extra is such a smart move… future you is going to be very grateful on those hectic nights! 💛
Oh my goodness! It hailed and stormed all day today in Phoenix AZ. This was the perfect comfort food dinner with complex deep flavors! So so good!
Aw, that sounds like the coziest way to end a stormy day! I’m so happy it hit the spot — those deep flavors really shine on nights like that. Thanks so much for sharing your note! 💛
One of my favorite soups! The second step took almost twice as long, but it was all worth it!
I’m so happy it’s one of your favorites! And thank you for mentioning the timing — those longer steps can be totally worth it in the end. I’m glad it turned out beautifully for you! 💛
What a great soup for a cozy night in! Loved all of the flavors. Highly recommend!
Aw, I’m so happy you loved it! It really is the perfect cozy-night-in soup. Thanks so much for the sweet note and the recommendation! 💛
This is such a cozy, delicious soup! I didn’t have sherry (in the middle of moving), but the taste was amazing. Cooking the onions low and slow is definitely key to melt-in-your-mouth goodness. I love the idea of cutting the bread into cubes versus one whole slice; so much easier to eat this way!
Aw, I’m so happy you loved it! Those slow-cooked onions really do make the magic happen, don’t they? And I’m with you on the crouton-style bread — so much easier (and more fun!) to eat. Thanks for sharing your note, especially in the middle of a move! 💛
Great recipe very good.
Will definitely make this again. Was wondering if anyone ever tried a TBS or so of balsamic vinegar ? I’m Guessing it would sweeten the broth.
I’m so happy you loved it! And yes — a splash of balsamic vinegar would be a lovely idea. It would add a little sweetness and depth to the broth. If you try it next time, I’d love to hear how it turns out! 💛
Thank you
Maybe a little ketchup would add a depth as well. But I believe you are spot on on cooking the onions.
I’m so glad you enjoyed it! And yes — a little ketchup could be something to try for extra sweetness. The slow-cooked onions really do make all the difference. Thanks for sharing your thoughts! 💛
This could not have turned out better! I loved the double cook on the onions. Thanks for sharing, I will be making this again!
I’m so happy to hear that! The double-cooked onions make such a difference, don’t they? I’m thrilled you loved it and plan to make it again. 💛
Can this be made vegetarian?
You could do a vegetarian version by using vegetable stock. The flavor will be more mild without the beef broth, but it will still be very tasty. I would make sure to use a vegetarian Worcestershire sauce to give the broth a little boost.
Thank you