French Onion Soup is essentially caramelised onion in soup form topped with cheesy bread. The French are genius!
Caramelising onions calls for patience, but it’s worth it. You’ll be rewarded with deeply golden, intensely sweet onions that forms an incredible flavour base for this French Onion Soup. For an effortless option, see how to caramelise onions in a slow cooker!
THE ICONIC FRENCH ONION SOUP!
French Onion Soup is probably one of the most epic soups in this whole wide world. And yet, the soup itself is made with very few core ingredients: butter, onions, flour and stock/broth.
The magic is in the caramelisation of the onions, cooked slowly for at least 40 minutes. And of course the crowning glory – the glorious melted cheese toast!! Because let’s face it – French Onion Soup without the cheesy toast is just onion soup. Meh!
CARAMELISED ONIONS – STOVE OR SLOW COOKER
The caramelised onions are the star of the soup (well, on par with the cheesy toast). Making caramelised onions the classic way on the stove takes upwards of 45 minutes for a giant mound like we use for French Onion Soup.
It’s not high-stress or high-energy effort. For most of the time, the onions are cooked over low heat so you just need to stir them every now and then.
It’s the sort of thing that’s good to make while pottering around the kitchen doing other things. My cast iron pot is 24 cm / 10″ wide and it was full to the brim with raw onions and took almost an hour to caramelise. If you have a wider base pot, it will be faster – probably closer to 45 minutes.
Though of course, if this all seems like too much effort for you…… introducing….
SLOW COOKER CARAMELIZED ONIONS!!!
Yes. You. Can!!!
I first learned of this from a reader then found this recipe on TheKitchn. Terrifically convenient and totally hands off, just throw the onions in, drizzle with butter or oil then leave on low for 10 hours.
This will get you 75% of the way there. The onions are browned a bit but lack the same intensity of flavour you get from caramelising on the stove.
So you do still need to cook the onions on the stove for 10 – 15 minutes to achieve the same true flavour. And while one may wonder what’s the point, there’s a big difference between cooking down onions for almost an hour on the stove vs 10 minutes.
Plus, no having to man-handle a gigantic mound of onions in a pot that’s too small (me, me!).
THE REST IS EASY!
Caramelised onions aside, the rest of the soup is effortless. Get all the tasty brown stuff off the bottom of the pot by deglazing it with a touch of wine. A touch of flour to thicken the soup every so slightly, a LOT of broth, and an optional sprig of thyme and bay leaves.
GOOD BEEF BROTH IS A MUST!
If you use store bought, which I often do, use a good quality beef broth/stock. I personally do not recommend any of the mainstream brands sold in Australian supermarkets. I use Maggie Beer and Moredough from Harris Farms (I stock up when it’s on sale!), or private labels from butchers.
If you can’t get good quality beef broth, use chicken or vegetable instead. I find that the quality of those by mainstream brands is much better than the beef stock. The beef is fine to use in things like gravy and stews, but not when it’s a key ingredient like in this recipe.
DON’T HAVE OVEN-PROOF SOUP BOWLS?
Neither do I! Can’t justify the storage for ONE soup that calls for it. Sure, it looks thoroughly dramatic to be served a piping hot bowl from the oven with the entire surface covered in bubbling cheese (and a piece of bread under there somewhere).
But actually, I prefer making grilled cheese separately and popping them in the bowl because the bread isn’t as soggy from absorbing the soup by the time it gets to the table.
And lastly, a little tip – try the grilled cheese with your very own homemade Artisan bread. It is mind blowingly easy and has been wildly popular with readers since the day I shared it! – Nagi x
FRENCH ONION SOUP RECIPE
WATCH HOW TO MAKE IT
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French Onion Soup
Ingredients
- 100 g / 3.5oz unsalted butter
- 1.25 kg / 2.5 lb brown / yellow onions , peeled, halved, thinly sliced top to bottom (Note 1)
- 3/4 cup (185ml) dry white wine , optional (Note 2)
- 2 tbsp flour , plain / all purpose
- 1.5 litres / 6 cups / 1.5 quarts good quality beef broth./stock OR chicken , low sodium/salt reduced (Note 3)
- 2 dried bay leaves (or 3 fresh) (optional)
- 3 sprigs fresh thyme (optional)
- Salt and pepper
Cheesy Toast
- 6 – 8 slices French baguette or other softish bread (Note 4)
- 100 g / 3.5 oz gruyere or mozzarella cheese, or other melting cheese of choice
- Fresh parsley or thyme leaves , for garnish (optional)
Instructions
Caramelise Onions (See Notes for SLOW COOKER option)
- Melt butter in a heavy based casserole pot over medium heat. When it starts to foam, add onions and stir to coat in butter.
- 30 min on medium low: Turn heat down to medium low. Cook for 30 minutes stirring every few minutes, until the onions have softened and are semi transparent.
- Salt, 20 min on medium high: Turn heat up to medium or medium high. Add salt, and cook for a further 20 – 30 minutes, stirring more regularly, until onions are deep golden and sweet.
Make Soup:
- Deglaze: Add wine, then simmer rapidly for 2 minutes until mostly evaporated, stirring to scrape the bottom of the pot.
- Flour: Sprinkle flour over the onion and cook for 1 minute.
- Add broth & herbs: Add broth, thyme and bay leaves.
- Simmer: Cover, lower heat so it’s simmering gently then simmer for 30 minutes.
- Serve: Season to taste with salt and pepper. Ladle into bowls. Top with 1 or 2 slices of cheesy toast.
Cheese Toast:
- Preheat grill / broiler to high.Toast each side of bread until light golden.
- Top bread with cheese, then grill until melted and some brown spots appear.
Recipe Notes:
Nutrition Information:
COMPLETE YOUR FRENCH MENU!
Pan Fried Fish with Brown Butter Lemon Sauce (Totally French! Poisson meunière)
Garden salad with French Vinaigrette
Chocolate Mousse (classic French)
LIFE OF DOZER
I KNEW I’d find a use for those onion goggles one day! 😂 (I don’t need them, I wear contacts so I’m onion-proof. Gimme all the onions to chop!)
French Onion Soup recipe originally published in September 2016 as part of a Chasseur cast iron cookware giveaway. Since this time, the recipe has evolved (adding more flavourings – wine, thyme and bay leaves) so new photos, words and recipe video added!
I just tried the french onion soup (without wine) and it tasted so good
I had two goes at this recipe. First time was in the slow cooker, and I don’t know exactly what I did wrong but the result looked like dishwater and tasted even worse. It went down the sink.
Undaunted, I tried again. I was using an old 4-oven Aga cooker, and I caramelised the onions on the hotplates, mostly the simmering plate but every so often on the boiling plate. When I added beef stock and brought it to the boil, I put it in the simmering oven for about 45 minutes.
I toasted the bread, topped it with pizza cheese and grilled that in the hot oven.
The soup came out rich, brown and absolutely delicious. I honestly have never eaten better soup, and the cheesy toast was sublime.
I tweaked the recipe a little. I added some garlic at the end of the caramelisation, just before the flour; and after the soup was cooked completely I tipped in a couple of shots of brandy. 5 Stars.
Help! why is my French onion soup bitter? I followed the recipe to a T
Hi Evelyn. try this for a nice way to bring out sweet onion flavor with out carmalizing slice onion not a white but a yellow. add lotsss salted butter to a skillet med low heat as it melts add onion cover and slowly simmer till done now proceed with recipe. for a whit onion soup ,Chicken Stock look for James Beard. white onion soup killer good
Hi Evelyn, sorry you had issues here – the onions didn’t burn did they by any chance? N x
Love French onion soup. A quick tip from me … try adding a little (2tbs per litre of stock) of brandy. It makes the soup sublime.
Delicious. So nice I made it twice. BUT – Second time round I added an extra cup of white wine and 2 tablespoons of onion powder and a teaspoon on cayenne pepper. Top quality grass-fed beef bone broth severely lacks the flavour that veggies etc add to classic beef stock. The extra wine and onion powder brought the soup to full flavour – it was undeniably better. The cayenne pepper was a personal touch and not necessarily for everyone. Interested to see your thoughts!
Love this recipe so easy to follow and the tears l shed for it 😊😊
This was amazing! So delicious. 10/10 from the whole fam!
Hi Nagi & everyother Nagi lover out in the world. Made soup as recipe………1 word……fabulous. also made the little Gougeres (your french cheese puffs) they mopped up all the little bits in the bowl that a spoon misses. Best ever. Pamela South Africa
What a great idea Pamela!! I love it! N X
How much salt domyou add after cooking the onions 30 minutes? I don’t think the recipe says?
Hi Lisa, just to taste – so to your personal preference 🙂 N x
Nagi, making this now & almost done so cannot wait to eat it! Not sure you have it there, but here in the US we have a product “Better Than Bouillon” & it’s better than any chicken or beef broth I’ve made myself or purchased in a store. I keep sampling the broth in this soup & yum!!! Thank you for your recipes, the ones I’ve tried have all been great.
Katherine! Don’t give away the secret! (I actually forgot about that jar of Better Than Bouillon but will be using it now; appreciate the reminder).
Oh.. my … god! Nagi you have converted me. I once had French onion soup so bad a restaurant I assumed that’s how it all tasted. Well I was so very wrong. Thanks for the tip on buying the premium stock. I would have never seen those brands if it wasn’t for you!! I’m making another batch today, can’t get enough 🙂 thank you
This soup was amazing! I made it today on the stove top and my sis in law made it in the crockpot. Another fabulous recipe….again I threw out my old recipe.
Just made the French onion soup, it was soooo good.
Can I just omit the flour to make this gluten free or would I need to substitute with an alternative?
Hi Gillian, use 1 tbls cornflour as a gluten free sub 🙂 N x
Thank you – made this last night and it was yum
This soup is devine! I absolutely love french onion soup but it is a bit of a labour of love so admittedly don’t make it very often. I’m so glad I came across this recipe when Miss 7 asked for it. Being vegan I used Maggie Beer’s vegetable stock and it worked beautifully. Definitely my go to from now on!
I’m so glad you loved it Deb!! N x
Amazing…i added a pinch of brown sugar and a few dashes of worscher sauce. Toasted borh sides of bread with butter. Piles of cheese and made cheese bread then sliced and put in soup.
Hi…I have also carmelized onions in the oven, sliced and sprinkledvwith oil . Also works
Don’t have to watch it ad much.
Delish Elizabeth! N x
Mmmmm… absolutely delicious!
It’s so much easier to do the cheesy croutons your way. I just used regular cheddar.
On reading your comments I decided to finally attempt making my own beef stock and WOWSERS – what a difference!!!
I read the ingredient list on beef stock cubes … it doesn’t even contain any beef!
I’ve made this twice in two weeks – sometimes all I can eat is soup due to my autoimmune disease which causes huuuuuge ulcers on my tongue and all down my throat and it’s so painful to eat anything solid – so thank you Nagi.
I’m so glad you love it Brigette, that’s great to hear! N x
I’m French and I absolutely love this soup !
That’s awesome, thanks so much for letting me know Sabrina! N x
Best French onion soup recipe. The search is over! I make this soup atleast once a month… I sub in Guinness though… mmmm… the wine does make it a little richer though…. sonic really like that aspect.
Thaaaaaanks so much for sharing!
Going to give this one a go tomorrow, prepared onions in advance. Other versions I’ve made call for the cheese rind to go in and out with the bay leaves so will do that, otherwise will follow this recipe. Wish me luck! 😀
You don’t need luck! 🙂 N x