French Onion Soup Cooks Illustrated

French Onion Soup Cooks Illustrated

I’ve always been nuts about French Onion Soup. From my very first taste! I remember it was at a little underground restaurant in Denver that I was introduced to French Onion Soup. I suppose these days we would call it a Bistro, and I was in my very early 20’s. I’ve had many French Onion Soups over the decades but none of them, at any restaurant, have been as good as this French Onion Soup Cooks Illustrated Version.

French Onion Soup Cooks Illustrated

French Onion Soup Cooks Illustrated


I do make other French Onion Soups (and love them, too) but it’s this recipe, these techniques that really taught me a lot about caramelization, technique, and flavor. It upped my F/O game for sure – and upped my game on many recipes!

About French Onion Soup Cooks Illustrated Version:

I still get super psyched over French Onion Soup. That first bite, digging into the bread and cutting it with the spoon on the bottom of the bowl – then lifting it, the bubbly, melted cheese forming a string or two…gently blowing so my tongue won’t get burned until I simply can’t wait any longer. And of course, I still always burn my tongue!!

And while I think any French Onion Soup is usually good, the best part shouldn’t be just the cheese! The soup, itself should be outstanding, the onions beautifully tender, and the flavor? Transformative. This, guys, is the one. I just wish I had a bowl of it right now…oh, wait I do! Jealous? No need to be, just make your own! I broke down the recipe for you as best I could. It’s easy but revolutionary, and I think you’re going find it sooooo doable!

French Onion Soup Cooks Illustrated

French Onion Soup Cooks Illustrated

Making French Onion Soup Cooks Illustrated Version:

Like many good recipes, this French Onion Soup relies on little more than basic ingredients (but the right ones) and time. Lots of time along with a good bit of effort and some attention. That’s what I call “love.” If you’re wondering how long? It’s gonna be a project, but so worth it.

Preparing the Onions, up to 20 minutes:

  • First, there’as the peeling and cutting of the onions. That can vary a lot depending on your method. The biggest take away I learned from Cook’s is to cut about 3/8ths inch thick and cut pole to pole for the perfect tender bite that holds together and cuts just right with a spoon.
  • I like to use my kitchen slicer, which cuts the 4 pounds of onions in literally three to four minutes. You can use a food processor, but honestly, I’d cut by hand (sharpen your knife) before using mine. A food processor won’t cut them pole to pole and you’ll have to open it and empty it multiple times. That’s up to you, though.

Caramelizing Onions, about 2 1/2 hours, almost all hands-off:

  • This is where the majority of the time in this recipe comes from. Cook’s Illustrated came up with an intriguing, mostly hands-off method, of baking the onions. They are baked for one hour, stirred, the lid is then left ajar as they continue to bake. Check at 40 minutes, stir, then continue to bake, checking every 15 minutes until light brown and almost dry.
  • Then the gorgeous caramelized brown color needed to flavor the soup is built up then on the stove. The onions brown stirring as needed for 20 to 30 minutes, stirring often until a crust builds up. Add a little water to deglaze and then cook a few more minutes, stirring, as needed until the crust builds a second time, six to 8 minutes.

Turning it into Soup, 35 minutes:

  • The Sherry is added and evaporated out.
  • Finally, the stocks, a little thyme, a bay leaf, and salt are added, all that crust build up on the bottom and sides of the pan is scraped into the soup and the soup is simmered for 30 minutes to develop and blend all the flavors.

Finishing the Soup, 25 minutes:

  • While the soup simmers, you’ll prepare the baguette slices (croutons).
  • Once the soup is done, place your bowls on a sheet tray, top with the crouton, sprinkle on the cheese and broil for several minutes. Let sit for a few minutes before serving.

Some Weirdness in the Soup:

  • Cook’s recommended a combo of beef and chicken stock and this really always makes the best soup; beef stock on it’s own can have an intense but not always “real” flavor and the chicken stock gives it balance.
  • I’m pretty sure this recipe was the first time I considered a combo of cheese on my French Onion Soup! It works so well, with the melty cheese and a little Parmesan for depth and bite.
  • While very good immediately, Cook’s Illustrated noted, and I found it to be true, that this soup is even better if made the previous day or even two. A “time-out” in the refrigerator takes any sharp bite out of the rich onion broth and produces a balanced soup. That makes it perfect to make on a lazy day and serve when needed.

Cutting the Onions:

Slicing onions pole to pole is pretty easy, but a kitchen slicer is really the way to go! A cheapie is adequate for most casual home use and runs about 30 to 35 bucks.


Caramelized Onions Three Ways

Cut your onion pole to pole.

Caramelizing Onions:

There are other ways to take care of those onions other than this oven method. Check out my post, Caramelized Onions Three Ways with links and lots of info! You can use one of the other methods in that post to caramelize your onions, just use the four pounds of onions called for in this recipe.

Here’s what your onions will look like at different stages using the oven method. It takes a bit of time but is mostly hands off and the flavor is incredible! And you are left with perfectly caramelized onions (as opposed to onions that are just browned) with a bare minimum of actual hands-on work.

Oven Caramelized Onions

Oven Caramelized Onions

Saving Money on This Recipe:

I always think of onions as being cheap, but it’s the sheer amount of them that adds up for this recipe. Honestly, you’re going to want big onions if possible; small scraggly ones might be cheaper but you can spend a lot of time on them and if you use a lot of small ones, you’ll lose enough from peeling that you might want to add in a couple to make up for them. Look for large bags of onions, the onions are usually larger and cheaper by the pound.

I stock up on broth and stock when it’s on sale during just about any food holiday! Usually, I buy big around Thanksgiving/Christmas and again around Easter when the Easter/Lent Sales are going on. Grocery store sales are generally much better than you’ll find at Aldi or your Buyer’s Club.

Day-old bread is great for this but do shop carefully for any cheese. There’s no reason to ever pay full price if you’re shopping well. Packaged refrigerator cheese goes on sale too often, keeps for weeks in the fridge and in a pinch, can be frozen. It won’t be good for eating out of hand if frozen (it is crumbly when thawed) but still melts well.

French Onion soup made November 2011, priced at $3.90. Repriced February 2014 for $5.41.

I hope you enjoy this recipe as much as our family has over the last couple of decades!! Serve this and I’m sure you’ll get rave reviews and be elevated to hero status! Please pin & share if you like it. As in any recipe, you’ll want to read it through the first time and take it step by step.



French Onion Soup Cooks Illustrated

French Onion Soup Cooks Illustrated


French Onion Soup Cooks Illustrated Version

  • Author: slightly adapted from Cook's Illustrated
  • Total Time: 3 hours 40 minutes
  • Yield: 6 servings 1x
  • Category: Soups
  • Cuisine: French


  • 3 tablespoons butter
  • 1 teaspoon salt
  • 6 large yellow onion, about 4 pounds, cut pole to pole about 3/8” thick
  •  water for deglazing
  • 1/2 cup dry sherry or 1/4 cup brandy
  • 4 cups low sodium chicken broth
  • 2 cups low sodium beef broth
  • 2 cups of water
  • 6 sprigs thyme, or about 1/2 teaspoon dried
  • 1 bay leaf
  • salt and pepper
  • 1/2 inch slices of baguette, 6 total
  • 6 slices Gruyere cheese, Provolone is good, too, or about a cup of grated. A combination of grated Gruyere and grated Parmesan is outstanding.


For the soup:

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 one teaspoon salt. (The salt helps draw out the excess moisture from the onions.) Cook, covered, one 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, checking the pan at about 40 minutes.

Stir and scrape the bottom and sides of the pan, then check every 15 minutes or so until they are soft and brown and nearly dry on the bottom. Remove pan if it appears to be in any danger of burning.

Note: The above is a deviation from Cook’s Illustrated – the first time I made this, following their directions my unions were burnt and dry the second time I checked them.

Carefully remove pot from oven and place over medium-high heat. Using oven mitts to handle pot, cook onions, stirring frequently and scraping bottom and sides of pot, until liquid evaporates completely and onions turn to a dark brown, 15 to 20 minutes, reducing heat to medium if onions are browning too quickly. Continue to cook, stirring frequently, until pot bottom is coated with dark crust, 6 to 8 minutes, adjusting heat as necessary. (Scrape any gooey fond that collects on spoon back into onions.)

Stir in 1/4 cup water, scraping pot bottom and sides to loosen crust, and cook until water evaporates and pot bottom has formed another dark crust, 6 to 8 minutes. If your onions are not a dark brown, repeat this step. (Look for the color in the bottom photo.)

Stir in sherry and cook, stirring frequently, until sherry evaporates, about 5 minutes.

Stir in broths, 2 cups water, thyme, bay leaf, and 1/2 teaspoon salt, 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 gently 30 minutes. Remove and discard herbs, then season with salt and pepper.

For the croutons & serving:

While soup simmers, arrange baguette slices in single layer on baking sheet and bake in 400-degree oven until bread is dry, crisp, and golden at edges, about 10 minutes. Set aside.

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, leaving enough room at the top for the croutons. Top each bowl with 1 or 2 baguette slices (do not overlap slices) and sprinkle evenly with Gruyère. Broil until cheese is melted and bubbly around edges, 3 to 5 minutes. Let cool 5 minutes before serving.


  • Cook’s Illustrated suggests using Swanson Certified Organic Free Range Chicken Broth and Pacific Beef Broth (more recently they suggest Rachel Ray’s Beef Broth). I’ve had very good results with the Aldi’s brand in a box.
  • If you like a thicker body to your soup, sprinkle a tablespoon of flour over the caramelized onion, cook a minute or two, then add your broth.

Per Serving: 623 Calories; 41g Fat (60.8% calories from fat); 45g Protein; 15g Carbohydrate; 4g Dietary Fiber; 134mg Cholesterol; 1145mg Sodium. Exchanges: 0 Grain(Starch); 6 Lean Meat; 1 1/2 Vegetable; 5 Fat.

Keywords: Bargain Meal of the Week, Beef Stock, Bread, Caramelized Onion, Cheese, Chicken Stock, Cook's Illustrated, Freezes Well, French, Kitchen Slicer, leftover bread, Leftovers, onions, Soup

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French Onion Soup Cook’s Illustrated is gonna up your French Onion Soup Game! The onions, deeply caramelized, the flavor outstanding! Oh and that cheese!! The onions are baked and then finished on the stove making this mostly hands-off! #OnionSoup #FrenchOnionSoup #CooksIllustratedFrenchOnionSoup #Soup


4 thoughts on “French Onion Soup Cooks Illustrated

  1. Deb

    Hi Mollie, I found you because the Cook’s Illustrated ( ATK ) site is down and I’m scrambling to find instructions for their F/O soup I just watched last week, and it looks like this one. Do you think I could use a good quality Bourbon ( Maker’s Mark 46 ) instead of sherry or wine? Also since I couldn’t download the TV video instructions I forgot about the Thyme. I’m going to start this tonight and reheat tomorrow, can I add the Thyme then or would it lack the chance to deepen in taste when it wasn’t included tonight.

    • FrugalHausfrau

      I am so sorry I totally missed replying to your questions. It’s been a few weeks now so I feel really bad! Hopefully you got things worked out. Mollir

  2. Nikki

    I have made quite a few of your recipes and been extremely happy with them, but I must say that I made this version of French Onion Soup today and it is the most disappointing version I have ever made. It’s not beefy, it’s not rich and thick, and it tastes like those beautifully browned onions were simply boiled in water. They browned beautifully and I should have stopped with this recipe at that point. This won’t deter me from other recipes, but I will not attempt this French Onion Soup version again.

    • FrugalHausfrau

      Hi Nikki, I’m so sorry this soup was a disappointment, but I do appreciate your honesty (and it wil help others who look at the recipe) and your continued confidence!! I have seen a few comments from you, so it’s appreciated! I work hard to try to make sure every recipe on my site is literally the best – obviously, it’s a goal that I may never reach, but continually aspire to!

      I’m not sure exactly what to say because it’s one of my faves! That being said, this recipe is over a decade old = while some might say a classic is a classic, in the last decade or so, especially with the explosion of food and recipes, tastes are becoming more sophisticated, methods updated, and the quest for flavor and more flavor is never-ending! At the same time there is a trend toward thicker rather than brothier soups, chowders and chilis.

      I am thinking this recipe is just too dated for your tastes! I’ve sent you another F/O soup recipe that you might want to try. You might want to add a tablespoon or two of flour to the onions when they are finished; stir them often for a minute or two so it loses its “floury” taste before adding the wine.


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