The Ultimate French Onion Soup

I made what I’ve always considered the best French Onion Soup for years and then I tried something new. This is amazing and it just took a new trick and a few extra minutes to go from the best to The Ultimate French Onion Soup; so worth it!

The UItimate French Onion Soup in Table Setting with Three Soups Bowls

I’ve been making this French Onion Soup forever; seriously, ever since the St. Louis Post Dispatch included it in the pages of their newspaper decades ago I jumped all over it. It’s really good and I’ll leave it as is on the blog because so many people from St. Louis have the same memories as I do and find that page. But this recipe for The Ultimate French Onion Soup has won me over too.

I picked up a copy of Cook’s Illustrated All-Time Best French Recipes not long ago. I’ve made almost every dish they include in the glossary but I’m not sure I’ve made the best version of each recipe. I’ve always loved Cook’s Illustrated.

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I appreciate the time they take to test and share those tests with readers. This Best Margarita recipe came from one of their publications probably 20 years ago and while I’ve fiddled with it a bit, it seriously is the best I’ve ever had.

I’ve had similar success over the years so I trust them and I was anxious to try something new. The ingredients are not all that unique from what I’ve always used but the method is quite different and yes, it really does make for a richer and even more flavorful variation than what I’ve done before; the trade-off is it takes a bit longer too.

The UItimate French Onion Soup Closeup

What’s different with The Ultimate French Onion Soup? Well for one thing the onions are cooked down in the oven. I liked this approach as it required less attention be paid than if cooking on the stove-top. But the most revolutionary part of the process was the caramelization and de-glazing of the onions during the process.

While my older recipe calls for cooking the onions down for one and a half to two hours, it never really specifies to cook the onions until caramelized. The difference is big; one creates soft, sweet onions and the other does the same but cooks them a bit longer til they start to turn brown and have a caramel color and are even sweeter.

But Cook’s Illustrated doesn’t stop there; it has the cook repeat this process multiple times until the onions turn a dark brown color before adding the remaining ingredients.

I loved the results of this technique, a soup even richer with an increased depth of flavor. But old habits die hard so I added some components of what I have always known and borrowed from my old recipe and that included adding paprika. It’s subtle but the black pepper and paprika are nice additions to a soup with sweet onions.

I also borrowed one thing I believe is a must from my tried and true version; I let the entire pot of soup sit in the refrigerator overnight before warming it and serving it the next day. It really does make a difference!

The UItimate French Onion Soup Closeup on Spoon

Finishing the soup requires some french bread cut into rounds and toasted and then added to the soup before being topped with cheese. The typical cheese used for French Onion Soup is Gruyère. If I’m honest I’ve often used Swiss because it’s handy and nowhere near as pricey as Gruyère; but honestly it’s not as yummy either.

This time around the choice was made for me. I had been asked to sample some Jarlsberg Cheese and had a block in my cheese drawer and a tasty sliver told me it would be perfect.

Jarlsberg® is a mild, semi-soft, part skim cheese made from cow’s milk and is famous around the world for its characteristic mild, sweet and nutty taste. It was that nutty component that I thought would make it be a good substitute for Gruyère. That it had a more robust flavor than plain Swiss was a plus and it was absolutely perfect, the cheese melted wonderfully and brought a great flavor profile to the finished dish.

Block of Jarlsberg Cheese

It’s prophetic that just this week, a woman who is in a group I’m in on Facebook that discusses food culture commented that she did not like leftovers and wondered why people make more than they needed.

I responded that I love leftovers; it’s like the work has been done and it’s an easy meal and they’ve been a part of my life since I was little. Heck they were lifesavers when I was a single mom; I enjoy cooking but I don’t need to make a new meal every single night!

Beyond that I mentioned that I felt some foods, soups included, seem to taste better after some time for the ingredients to meld in the fridge. She wasn’t buying it and that’s OK, to each their own right?

Still, this soup falls into that ‘overnight in the fridge’ category and it’s absolutely necessary. I tried a quick bowl of this prior to refrigeration and it doesn’t come close to the richness of flavor that is evident after an evening spent chillin’ in the fridge.

So Cook’s Illustrated might not have needed it but I did. Taste testers agreed, citing it the best French Onion Soup they’ve ever had. That’s high praise indeed; especially since one of them has never been a fan and she finished off that bowl!

It’s a bit time intensive but still easy to make and don’t let the warmer weather stop you; we will be eating The Ultimate French Onion Soup all year round. It’s so good I’m not letting some summer heat stop me! If you make it and have leftovers? I freeze some in flat pouches that are so easy to warm up whenever the urge strikes you.

Try it and let me know if you don’t think it’s the Ultimate too!

PIN IT! ‘The Ultimate French Onion Soup’

 The Ultimate French Onion Soup Served in Soup Crocks
The UItimate French Onion Soup Closeup

The Ultimate French Onion Soup

A version of the recipe I've loved forever, but using a method to cook the onions even longer. Absolutely the best.
5 from 50 or more votes
Prep Time 20 minutes
Cook Time 5 hours
Total Time 5 hours 20 minutes
Course Soups and Stews
Cuisine French
Servings 8 Bowls of Soup
Calories 550 kcal


  • 3 tablespoons unsalted butter cut into 3 pieces
  • 4 pounds about 6 large yellow onions halved and cut pole to pole into 1/4-inch-thick slices
  • 1 teaspoon salt
  • 2 cups water plus extra for deglazing
  • ½ cup dry sherry
  • 4 cups chicken broth homemade or canned
  • 2 cups beef broth homemade or canned
  • 6 sprigs fresh thyme tied with kitchen twine
  • 1 bay leaf
  • Ground black pepper
  • 1 tablespoon paprika
  • 1 small French baguette cut into 1/2-inch slices
  • 8 ounces shredded Jarlsberg or Gruyère about 2 1/2 cups


  • Adjust oven rack to lower-middle position and heat oven to 400 degrees. Generously spray inside of heavy-bottomed large (at least 7-quart) Dutch oven with nonstick cooking spray.
  • Place butter in pot and add onions and 1 teaspoon salt. Put in oven, covered, 1 hour (onions will be moist and slightly reduced in volume).
  • Remove pot from oven and stir onions, scraping bottom and sides of pot. Return pot to oven with lid slightly ajar and continue to cook until onions are very soft and golden brown, 1 1/2 to 1 3/4 hours longer. Remove from oven and turn oven off.
  • Place pot over medium-high heat. Cook onions, stirring frequently and scraping bottom and sides of pot, until liquid evaporates and onions brown, 15 to 20 minutes. Continue to cook, stirring frequently, until pot bottom is coated with brown crust, 6 to 8 minutes, adjusting heat as necessary. Stir in 1/4 cup water, scraping pot bottom and cook until water evaporates and pot bottom has formed another dark crust, 6 to 8 minutes. Repeat process 2 or 3 times, until onions are very dark brown. Stir in sherry and cook until sherry evaporates, about 5 minutes.
  • Stir in broths, 2 cups water, thyme, bay leaf, salt, pepper, and paprika, scraping up any final bits of browned crust on bottom and sides of pot. Increase heat to high and bring to simmer. Reduce heat to low, cover, and simmer 30 minutes. Remove and discard herbs, then season with salt and pepper.
  • Let soup cool completely then cover and refrigerate overnight. Remove from the refrigerator an hour before serving.

For the Croutons

  • Arrange baguette slices on baking sheet and bake in 400-degree oven until bread is dry, crisp, and golden at edges, about 10 minutes. Set aside.

To Serve

  • Heat soup to almost boiling. Adjust oven rack 6 inches from broiler element and heat broiler.
  • Set individual broiler-safe crocks on baking sheet and fill each with about 1 3/4 cups soup. Top each bowl with 1 or 2 baguette slices (do not overlap slices) and sprinkle evenly with cheese.
  • Broil until cheese is melted and bubbly around edges, 3 to 5 minutes. Let cool 5 minutes before serving.


Homemade or Canned Broth? What’s the best? Honestly if time was of no matter, I would love to make this with homemade beef and chicken broth. But of course it’s not so I’ve always used canned broth. It is one thing I don’t use store brands for though; I’m a fan of Swanson Broth and it’s never failed me!
This soup freezes well in individual servings too. Can be reheated in the microwave or on the stovetop and then finished with the toasted bread and cheese.


Nutrition Facts
The Ultimate French Onion Soup
Serving Size
1 Serving
Amount per Serving
% Daily Value*
* Percent Daily Values are based on a 2000 calorie diet.
Keyword caramelized onions, French, gruyete, soup
Tried this recipe?Let us know how it was!

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    1. Thanks Jon! We love it…and the teenage boy across the street loves to slice onions on my small kitchen slicer so he does the worst part! 🙂

    1. Not to my knowledge. I’ve seen recipes for French Onion Leek Soup but it’s always been a combination of white onions with leeks. When I think about it, I can’t imagine sauteing leeks for the length of time it takes to extract the best flavor, they are so thin I would think they would fall apart!

      Although have to admit, adding some leeks sounds like a great idea and I might have to do that next time!

    2. 5 stars
      We followed the recipe and timeline before eating and I must say, this is hands down one of the best French onion Soups I’ve ever had.

      -A Dad

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