Slow Cooker Onion Soup ♥

Slow Cooker Onion Soup
Today's homey soup recipe: Onion soup, French onion soup I'd guess you could say, because the onions are cooked in the slow cooker with red wine and good stock until soft and sensual ribbons, then finished under the broiler with toasted bread and melting cheese. The soup itself is Weight Watchers Friendly, just 100 calories a cup and WW 3 PointsPlus. Low Cal (for onion soup).

~recipe & photo updated & reposted 2014~
~more recently updated recipes~

Yes, it's the lovely onion soup cooked for long hours in the slow cooker, then tucked with toast and topped with cheese and then, finally, sipped and slurped, slow bite by slow spoon. Is it French onion soup? What makes an onion soup French, per se? I don't know that answer but I do know, a slow-cooked onion soup is delicious stuff.

The bread and cheese add carbs and calories to this dish. I enjoyed the soup, plain – so the bread and cheese aren't necessary, if supremely tasty. Moving on to the cheese-topped version, I was surprised by how much cheese was required just to achieve what looks like a thin layer in the photo (though it tasted like plenty, no one felt cheated). What those home and restaurant bowls with their thick layers of cheese must add up to, calorie-wise, point-wise, I don't want to know (or eat).

SOUP's ON In February 2007, I hosted a food blogger event called "Soup's On". My first soup contribution was spare and simple peasant food, Peasant Cabbage-Tomato Soup. My final contribution is this Slow Cooker Onion Soup, also spare and simple and yet extraordinarily rich, the food of kings that even peasants can afford. Walk through Soup's On, it's a grand collection of soup recipes from food bloggers all over the world. Many thanks to everyone for participating!


Hands-on time: 20 minutes to start, 20 minutes to finish, occasional attention in-between
Time to table: about 8 hours (truly best when made 24 hours ahead)
Makes 11 cups

3 tablespoons unsalted butter
4 pounds large yellow onions, trimmed, peeled and sliced in 1/4-inch half rings

1 cup dry red wine
2 tablespoons port
5 cups beef stock
1 tablespoon melted butter
1 tablespoon flour
Salt & pepper to taste

TO SERVE, per bowl
1 thick slice good bread, toasted
1 ounce Emmentaler or Gruyere or another good melting cheese, sliced thin

CARAMELIZED ONIONS Melt the butter in a large slow cooker on HIGH. Add the onions as they're sliced, stirring to coat with fat with each addition. Cover and let cook for 1 hour, stirring occasionally. Decrease the temperature to LOW. Let cook, stirring occasionally, til browning, about 4 hours. (In 2007, this took 6 hours, in 2014, 3 hours. This is why I slow cookers are so hard, there's just such variability in heat and timing.)

ONION SOUP Add the wine, port and stock. In a small bowl, stir together butter and flour, whisk it into the soup to thicken slightly. Season to taste, then cook for 2 hours. Taste and adjust seasoning.

LET REST While the soup is technically "done" at this point, the flavors meld when left to rest overnight. In fact, if you taste it here, you're going to wonder what all the fuss is about.

TO SERVE Bring the soup back to a boil either in the slow cooker or on the stovetop. Place a scoop of onions in each bowl, top with a bread slice, then fill the bowl with liquid. Top with cheese and place under the broiler until cheese melts and begins to brown, watching carefully, the cheese can go from melty to outright burned in a nanosecond.

Yellow onions are the right choice for onion soup. So-called "sweet" onions are best for eating raw, not for cooking, because they turn muddy flavored once cooked.
Be generous with the salt, especially if using homemade beef stock that hasn't been seasoned.
I like this soup served plain, without the bread and cheese. It's not pretty, though, so a little fresh parsley adds color and brightness.

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A Veggie Venture is home of "veggie evangelist" Alanna Kellogg and the famous asparagus-to-zucchini Alphabet of Vegetables.


  1. French Onion Soup (I have no sources to back this up, but I call anything made of caramelized onions that) has to be my all-time favorite. Well, one of them. I've only made it once this winter - I suppose I should be thankful our winters last long enough that there's still time for another one!

  2. I love that no sugar is added to this for carmelizing the onions. Will try it for sure. FWIW, in college I worked at a French restaurant where this was a popular dish. They served it with mozarella cheese (not fresh mozarella.) In those days I had no thoughts at all about the fat content, but now I might try that as a lower fat alternative. As I remember, it tasted great.

    Thanks for all the great soup recipes.

  3. It's been a blast reading all these soup recipes! Thanks for compiling them.

  4. i'm going to try this in the pressure cooker. thanks, alanna. you take the most gorgeous pictures.
    - bee

  5. French onion soup is DH's favorite soup and I've always been too afraid to attempt it. This recipe looks simple enough that I should definitely give it a try. Thanks Alanna!

  6. Oh Alanna, saying that the bread and cheese are not needed to enjoy onion soup is sacriledge. You will be punished by the Gods. The soup is merely a nice garnish for the ooey, gooey, broiled cheese. Your soup could be an ad on TV for the cheese federation (or whoever it is who makes those wonderful "I left him cheeeeeese" commercials). Just kidding. I know the calories and fat are all in the cheese but who can resist it? Okay, who besides me has no willpower when it comes to cheese? :-)

  7. Nothing says loving to my hubby like something from the slow cooker ... and he's a big onion soup fan ... so this is going into the must try file!

  8. That is a gorgeous bowl of soup, Alanna -- a fitting end to the month of soup! I like my onion soup with a mixture of sweet, red, and yellow onions (and sometimes a shallot or 2 if I have them). Winter is passing here, but I know I will return to your round-up as soon as a chill hits the air again. Great idea!

  9. I just made an onion soup yesterday and used dry vermouth instead of white wine. Also added minced garlic once the onions had sweated and it was the best onion soup I have ever eaten. Many years ago I lived in Los Angeles and went to a restaurant whose specialty was French Onion soup. This far surpassed theirs so I highly recommend trying both additions.

  10. Deinin ~ Long winters are good for many things, yes?!

    Kalyn ~ The onions caramelize themselves, it's very cool.

    Homesick ~ A blast of soup, yes!

    Bee ~ I'd love to know how this goes in a pressure cooker, how the 'speed' cooking compares to the 'slow' cooking. And you make my day re the photo, take THAT, my photo critics (and kind encouragers ...)

    Sally ~ Oh then this one has DH's name all over it.

    Glenna ~ I know, but I can't help it any more than you can help little willpower for cheese. My own take is that information is empowering, that I happily make food choices, a balance of flavor and enjoyment and the calorie/etc consequences. But I'm happy-happy-happy to concede that melted cheese and bread with onion soup are indeed a huge temptation.

    FJK ~ I love that must-try file concept. Some times we actually do what we 'must'!

    Jennifer ~ Love the idea of the mixed onions and shallot, leek too perhaps? I love how soup 'bridges' the seasons.

    Elaine ~ Great idea, the vermouth. I'd be tempted with sherry, too. And the garlic, of course!

  11. Veggie Venture: With Beef stock????

  12. Hi Anonymous ~ A Veggie Venture is all about vegetables but is not 100% vegetarian -- even though it is an largely vegetarian and mostly vegan. There's more information about this in this Note to Vegetarians. Hope this answers your question!

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Thank you for taking a moment to write! I read each and every comment, for each and every recipe, whether a current recipe or a long-ago favorite. If you have a specific question, it's nearly always answered quick-quick. ~ Alanna