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Overnight French Onion Soup

When I was a kid, I haaaated cheese.* Just walking near the cheese display at the supermarket made me gag. It wasn’t until I grew up that I discovered the wonder that is French onion soup. Once my eyes were opened, I’d order the soup almost any time it appeared on a menu—mostly for those crispy edges, the part that drips over the side of the crock. I’d leave the larger glops to sink to the bottom of the bowl, since they were too obviously, y’know, cheese, and gorge on sweetly caramelized onions and crusty, broth-soaked bread. And then came Weight Watchers. All that cheese can’t be good for a person, I figured, so reluctantly I gave it up.

Until this week, I’d never even thought to make it at home. But then I went to a press event at Whole Foods, and they gave us sample loaves of uber-healthy sprouted wheat bread. This stuff is so hearty, I knew Harry would never go for it; heck even I almost didn’t. It’s intense. But waste not want not and all that, so I needed a way to use it up. Except it was too dense for French toast or bread pudding. Too overwhelmingly wheaty-tasting for sandwiches. My best bets were breadcrumbs or croutons. And as soon as the word “crouton” popped into my head, so did an image of French onion soup.

I knew from reading Lora Brody’s book Slow Cooker Cooking that caramelized onions are a cinch in the slow cooker. Her recipe calls for an entire stick of butter, which, no. I can’t. Trust me, you can get deliciously caramelized onions with much less fat. And if you let the onions melt in the cooker overnight, you wake up to the most amazing aroma, the base for a soup that simmers the rest of the day and yields such deep layers of flavor, it can stand up to the heartiest of breads. Bonus: The flavor-to-effort ratio here is off the charts.

* Mostly, I still do. But I can understand the appeal, so I don’t make a big stink about it. (Get it? A “big stink” about cheese?)

Overnight French Onion Soup
Serves 4
Weight Watchers: Each serving is 10 PointsPlus

If you’ve got other uses for caramelized onions (and hey, who doesn’t?), double the quantities of onions and oil, and remove half of them in the morning before proceeding with the soup.

6 large onions, halved and sliced thin
2 tablespoons olive oil
3 sprigs fresh thyme, or 1 1/2 teaspoons dried, divided
4 cups reduced sodium beef broth
1/2 cup sherry (or cognac, brandy, port, or wine of either color—this is a flexible recipe)
1/2 cup apple juice or cider
Salt and pepper
1 bay leaf
4 slices crusty bread (I used a sprouted wheat, but traditionally it’s made with, duh, French bread)
2 ounces Gruyere cheese, shredded
2 tablespoons grated Parmesan cheese

  1. Before you go to bed, toss together the onions, olive oil, and thyme sprigs in a slow cooker. Set it to Low.
  2. In the morning, you’ll have gorgeously caramelized onions. Remove the thyme stems and stir in the broth, sherry, apple juice, salt and pepper, and bay leaf. Cover and cook on low 8-10 hours (you could also have soup for lunch by setting it to high for 4-5 hours).
  3. 40 minutes before you want to eat, preheat the oven to 350. Put the bread slices on a baking sheet and toast for 10 minutes on each side, until they’re nicely dried out. Raise the oven setting to broil.
  4. While that’s going, taste the soup and adjust seasoning; remove the bay leaf. Portion the soup into 4 flame-proof crocks set on a rimmed baking sheet (I don’t own crocks, so I used one medium round casserole dish). Put one slice of toasted bread in each crock, and sprinkle with 1/4 of the cheeses.
  5. Broil the soup 3-4 inches from the flame for 3-5 minutes, until the cheese is browned and molten. Let cool slightly before serving.

MAKE BABY FOOD: Those onions are so meltingly soft, they’re perfect for young eaters. Puree some with the broth, or fish some out using a slotted spoon and serve as finger food, along with some shredded Gruyere. There is a bit of alcohol in this dish (1 ounce of sherry per adult serving)—most, but not all, of it will burn off in cooking. If you’d rather not give your baby even a whiff, reserve some of the caramelized onions before you add the remaining ingredients.

This Post Has 12 Comments

  1. Melanie @ Frugal Kiwi

    I LOOOOVE this idea. Must make. And soon. French Onion Soup is one of my all time favorite dishes.

  2. Jesse

    Any thoughts on how pareve beef boullion cubes might work in place of actual beef broth (assuming they make those…dont really know. i always buy the chicken ones)? I love french onion soup, but the kosher in me just can't get past the beef/cheese situation. Not sure if the boullion would lack flavor or if it would be ok.

  3. debbie koenig

    Jesse, I was wondering about that myself–kashrut is part of the reason I didn't discover this until I was older! I think it would be ok, just watch the sodium–bouillon tends to be super-salty. The other option would be to use low-sodium vegetable broth & add a shot or two of soy sauce for umami.

  4. Jesse

    I like the soy sauce/ veggie broth idea! I might just have to try it and see how it goes. I'll let you know if I do.

  5. MyKidsEatSquid

    What a great idea–french onion soup in the crock pot. I'm definitely trying this this week. This is one of my dh's favorite dishes.

  6. dmrredd

    I put the onions in last night and woke up to the smell of DELICIOUSNESS! I had to tweek it a bit, I didn't have sherry or gruere, but it came out awesome without. I will definately have to make it the next time with them! And did I mention EASY? This is so simple to prepare.
    Next time….I'm DOUBLING IT!!!

  7. Stephanie Stiavetti

    This looks incredible, and it's gf. Winning combination, and I need something to keep me warm in this weather!

  8. debbie koenig

    Jesse, be sure to report back–if it's a hit, I'll add a note to the recipe itself.

    dmrredd, I'm so glad you liked it!

  9. Coreopsis

    I need to drag myself away from here. HELP! It never occurred to me that one could carmelize onions over night. I think I'll do it tonight. I usually carmelize onions in a heavy cast iron skillet (with hardly any oil–maybe a tablespoon for as many onions as I can get in…..)

  10. SusanRanis

    This sounds wonderful–my favorite soup and very little effort. I am scheming to start it. The only problem, while the cooking part seems simple, I need help with the labor involved in hauling a ladder into the kitchen, climbing up, rummaging around in the upper dungeons of cabinets and finding the crock pot. I wonder if there is another blog for this problem.

  11. Allison

    I made the overnight French onion chicken from your cookbook and froze all the leftover onions and liquid, which was a large Tupperware amount. How would you go about turning that into French onion soup? Is it something I can slow cook again or no because it already has been? I hate to let it go to waste. Thanks!!

    1. Debbie Koenig

      What a smart idea, Allison! Since those onions have been slow-cookered twice already (once to caramelize, and then again to make the chicken) I don’t think you need to go that route again–I’d think you could put the defrosted leftovers into a big pot, add a quart of beef broth, and let it simmer for 30 minutes to an hour so the flavors can blend. Then proceed with this recipe and you’ve got French Onion Soup.

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