Crockpot French Onion Soup

Crockpot French Onion Soup | Cookie Monster Cooking

Are you ready for part two of Crocktoberfest?  I bet your crockpot is definitely ready.  Because today we are sharing main dish recipes.  Which is probably what I use my own crockpot for most often.

And my contribution?  Crockpot french onion soup.  And oh is this a good one.  For years (no joke) I’ve tried to find my favorite way to make french onion soup – this search began long before I even started this blog.  After a lot of experimentation, I decided I preferred to do it in the crockpot.  But then I couldn’t find a recipe that I liked enough to make over and over again.  Let’s just say that we’ve eaten quite a bit of french onion soup over time.

But my husband and I finally agree – this is our personal favorite.

Crockpot French Onion Soup | Cookie Monster Cooking

Now this is not a set it and forget it type of recipe.  But the crockpot still does most of the work for you and in my opinion is definitely worth it for the end result.  The onions get so wonderfully caramelized over time, which creates the perfect base for this soup.  So plan to make this a weekend type of recipe.  And it makes a ton of food – we always freeze at least half for another time.

So once again I’ve teamed up with my friends to bring you 17 other delicious main dish crockpot recipes!  Yes, 17!  So be sure to mosey on over to their sites to take a look.  And if you love crockpot dishes then also check out #crocktoberfest2013 on facebook, twitter, and instagram to find all the other recipes that will be shared this week.

Baja Chicken Soup from Around My Family Table
Crockpot Pot Roast from Eat Drink Love
Crockpot French Dip from White Lights on Wednesday
Chicken Enchilada Soup from {I Love} My Disorganized Life
Grammy’s Crock Pot Turkey Legs from Dizzy Busy & Hungry
Beef & Barley Soup from Peanut Butter & Peppers
Beef Stew from Curry & Comfort
Sweet Potato Cheddar Slow Cooker Soup from Homemaking Hacks
Crock Pot Green Chili Chicken from Mom Endeavors
Slow Cooker Carnitas from Foodie Tots
Italian Pork Chops with Parmesan Noodles from Pink Cake Plate
Slow Cooker 15 Bean Soup from 365 Days of Crockpot
Slow Cooker Tomato & Brown Sugar Pork Chops from Brie Brie Blooms
Slow Cooker Sesame Beef from Slender Kitchen
Slow Cooker Italian Beef Sandwiches from Dinners, Dishes, & Desserts
Pumpkin Chili from Celebrating Family
Refried Beans without Lard from Kitchen Treaty


Crockpot French Onion Soup
Yield: 8 to 10 servings
For the base:
  • 6 tablespoons unsalted butter, cut into pieces
  • 4 large yellow onions, thinly sliced
  • 8 cups low sodium beef broth
  • 1 bay leaf
  • 2 cloves garlic, minced
  • ¾ teaspoon salt
  • ½ teaspoon pepper
For serving:
  • 4 to 5 cups cubed crusty bread (I use a multi-grain loaf)
  • freshly shredded gruyere cheese
  1. Turn on your crockpot and set it to high. Add in the butter chunks and then put on the cover. Once the butter is melted, add in the onions. Mix to combine. Put on the cover and let cook for about 1 hour.
  2. After the first hour, give the onions a good stir. Place a double layer of paper towels under the lid (which will help to absorb some of the moisture - you’ll want to replace this layer about 2 to 3 times during the cooking process). Continue to cook on high for about 5 to 6 additional hours, stirring the onions about every 35 to 45 minutes.* You want the onions to be a caramel color. Toward the end of the cooking time, keep a closer eye on the onions (you don’t want to let them burn and may need to stir them more often).
  3. Discard the paper towels. Turn down the crockpot to low. Add in the broth, bay leaf, garlic, salt and pepper. Cover and cook for 1 hour. Discard the bay leaf and then taste and adjust with additional salt/pepper if needed.
  4. Preheat your broiler. Place oven-safe bowls or crocks on a baking sheet. Spoon the soup into the bowls. Place a handful of bread cubes in each bowl and then sprinkle the top with some of the cheese. Broil for about 2 to 4 minutes, until the cheese is golden and bubbly.
Depending on your broth, you’ll need to adjust the amount of salt to your taste. I’ve found that different brands of low sodium broth will vary in how salty they are - so just taste and adjust as needed. You can always add more salt later, so start with a lower amount and go from there.

*I have a small 4-quart crockpot, so it may take less time for caramelizing your onions if your own crockpot is larger. Just keep an eye on them.

Cookie Monster Cooking


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Skillet Apple Crisp
Pumpkin Spice White Hot Chocolate
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  1. I did my onions overnight so they were a lovely deep caramel then just added stock etc in the morning and ready for tea! Delicious.

    1. If you’re not going to use beef broth, I would go with vegetable stock rather than chicken. The beef stock is at least partially for color, as well as flavor, and chicken won’t give you that. I generally find that vegetable stock is a little darker in color than chicken

    2. I would suggest a combination of vegetable broth and a bit of red cooking wine. This will lift the flavor of the onions and give that rich flavor you’re looking for in an onion soup.

    3. I’m pollo-pescetarian, so I don’t eat beef either. A really great sub for beef broth is turkey or duck broth; both give you that “darker” flavor that dishes like this crave. You can make a broth out of any bird that’s mostly dark meat, and you will get that same rich flavor without the cow.

  2. This French onion soup was excellent. I used only 3 Tbsp. of butter . I stirred the onions after about 90 minutes, then added the broth after 4 hours of cooking on high. Cooked it for another 90 minutes, added 1/4 cup of sherry and cooked it for 30 minutes more.

  3. I am thinking of making this receipe for my Christmas Lunh at work…so my question is have you ever reheated once you baked. So, could I cook it the night before then when I get to work plug in my crockpot and put on warm?

    1. Hi Teri! I’ve definitely re-heated the soup base itself (i.e. the onion/broth) – that works great. And then I’ll just spoon into the crocks and bake off when needed. But I’ve never re-heated once baked with the bread/cheese.

  4. Catching up on my favorite blogs now… Love the idea of Crocktoberfest! And what an interesting way to make French onion soup! I will need to try this, I’ve always made it the more “traditional” way (caramelizing the onions in a pan, etc.). Looks delicious and perfect for fall. My crockpot has been sitting in my cupboard for years, now I actually have something to use it for!

  5. This looks fantastic Ashley! French onion soup sounds so comforting and perfect for this time of year. I have never tried making it in a crockpot and love the idea of caramelizing the onions directly in the crockpot. Enjoying all these great recipes for my crockpot – pinned :)

  6. Making French onion soup in the crockpot is a great idea! I love caramelized onions, but I’ve always hated that I essentially need to be standing over the stove (or just a few steps away) for the entire time the onions caramelize. This seems like a great solution!

  7. Ah! French Onion Soup, the ultimately warming comfort food in my mind (especially with the croutons and melted gruyere….yum!!) Another gorgeous post Ashley. I think my case for a Crockpot purchase is strengthening by the day… :-)

  8. Yum – French onion soup sounds so good right now! Thanks for sharing the best of all your experimentation. I recently saw a post about making caramelized onions in the crockpot and I was really intrigued because I love it but have only made them once or twice. I think your soup pretty much does that in the first step so it does work, right? Just need to watch it towards the end to make sure it doesn’t burn? I need to give it a try!

    1. Yes! That’s exactly what you do in the first part of this recipe! It makes it so much easier (you still need to give them a stir every 45 minutes or so (and more often toward the end) but it still seems easier this way than on the stove! Well at least to me : )

  9. I love French Onion Soup and only had it for the first time recently. That’s a great tip to freeze the soup, I always forget about doing that and it’s nice to know this soup freezes well. Okay, now I REALLY need to get a crockpot!

  10. I love the idea of a slow cooker French onion soup! Caramelizing those onions takes forever on the stove top, so this sounds like a great way to enjoy the soup without going to so much trouble! Yours looks absolutely delicious.

    1. I definitely prefer caramelizing them in the crockpot – less hands on time (even though it still takes a long time) and it seems to contain the onion smell a bit too … you just get a nice smell versus a seeps into my clothes and furniture type of smell! haha

  11. I do love crock pot recipes!!! I’ve been getting a lot of use out of main lately. I use mine all year round, but definitely more so in the cooler months. This French onion soup sounds wonderful! The house would smell so good when I got home having this cook all day!

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