Wednesday, January 17, 2018

Slow Cooker French Onion Soup (With Video)

Slow Cooker French Onion Soup is ridiculously easy to make. It is incredibly flavorful and you can top it with as much cheese as you want!

Slow Cooker French Onion Soup is one of the easiest recipes you can make in your slow cooker. This soup is also very budget friendly, unless you decide to spend all your dollars on the most expensive cheese, and that will be totally worth it, because cheese equals happiness. But guys, if you ever wanted to try to make French Onion Soup, this slow cooker version is fool-proof and also makes the most amazing and flavorful soup you will ever taste!

Hey guys, it's Catalina from Sweet and Savory Meals here. I am happy to be a contributor on TSRI and add recipes to Donna and Chad's already great collection. A few weeks ago I introduced you to this amazing Slow Cooker Baked Potato Soup, that now has more than 10M views on Facebook! Since we are in full-force soup season (aka cold winter) I wanted to share with you another soul warming soup recipe. I hope you enjoy this Slow Cooker French Onion Soup and if you are looking for more delicious soups, check this Slow Cooker Chicken Tortilla Soup!


  • You can technically use other variations of “white” onions, but sweet onions work best in this recipe. Also, please do NOT use red onions.
  • This recipe takes a long time to make, not actively, but the slow cooker will be on for half a day. I recommend starting early morning to cook the onions. Considering that you will have to stir them halfway.
  • If you want to cut down the cooking time, you can brown the onions on the stove, until perfectly brown and caramelized. You will have to do this on low heat, not to burn the onions, for about 1 ½ to 2 hours. You will have to add a little liquid if needed. When transferring the onions to the slow cooker, transfer the juice from the onions as well. 
  • The thyme and bay leaves are optional, they add great flavor, but if you don’t have any on hand, you can skip these.
  • When it comes to adding the sugar, I used 2 teaspoons only and also, preferably use brown sugar as it adds that caramel flavor when combined with the onions. You can add more sugar, if you prefer the soup sweeter.
  • I like to add the sherry vinegar and Worcestershire sauce to the onions, for a deeper flavor. You can also add these when you add the beef stock.
  • You can also use asiago cheese, or a mix of Gruyere and asiago.


  • Slow Cooker - the slow cooker is almost my most used kitchen gadget, especially during fall/winter! It's just so convenient, and lets face it, it makes comfort food taste even better!
  • Worcestershire Sauce  - enhances the beef flavor in recipes that use beef, or in this case beef stock.


With love from our simple kitchen to yours. 

Do you   love  TSRI?  Don't miss another recipe.  Click here to Subscribe to The Slow Roasted Italian by Email and receive new recipes in your inbox every day!

Don't miss a thing! Follow us on Facebook Twitter Pinterest | Instagram ❤ ❤ ❤  

Check out more of our favorite soup recipes:  Click on the image or the bold recipe title and it will open each one in a new tab!!!

BEST EVER Hearty Beef Soup!  With juicy tender chucks of beef that melt in your mouth and a glorious rich soup loaded with vegetables it is truly the ultimate comfort food.

25 Minute Bacon Beer Cheese Soup with Chicken - BACON.BEER.CHEESE.SOUP - You're welcome.

Slow Cooker Potato Soup is easy to make, creamy, thick and packing all the delicious flavors of a fully loaded baked potato!

See how easy this Slow Cooker French Onion Soup is to make. Watch the video!!! 

Slow Cooker French Onion Soup 
SERVES 8  |  PREP TIME 15 Min  |  COOK TIME 16 Hours

3 pounds sweet onions, thinly sliced
4 tablespoons unsalted butter, melted
2 teaspoons brown sugar
2 teaspoons sherry vinegar
1 tablespoon Worcestershire sauce
5 fresh thyme sprigs
3 bay leaves
6 cups beef stock
Kosher salt and freshly ground black pepper, to taste
1 (12-ounce) French baguette, sliced
2 cups Gruyère cheese, shredded

Add the thinly sliced onions to a 6-qt slow cooker. Stir in butter, brown sugar, 1 teaspoon salt, sherry vinegar and Worcestershire sauce.

Cover and cook on high heat for 8-9 hours or on low for about 12-14; or until onions are caramelized and browned. Make sure to stir halfway, as needed, to prevent burning.

Stir in beef stock, season with salt and pepper, to taste and add thyme sprigs and bay leaves. Cover and cook on high heat for 2-3 hours or on low for 4-5 hours. When ready discard thyme and bay leaves.

Preheat oven to broil.

Place baguette slices onto a baking sheet and broil until golden brown on both sides, about 1-2 minutes per side.

Divide soup into ovenproof bowls, place the bowls on a baking sheet. Top with toasted baguette slices, about two slices per bowl, the bread should cover the soup; top with lots of shredded cheese.

Place into the oven and broil until the cheese is bubbly and golden brown, about 2 minutes.

Serve immediately.

Recipe developed by Catalina Castravet for The Slow Roasted Italian
Copyright ©2018 The Slow Roasted Italian – All rights reserved

Disclosure: Posts may contain affiliate links. If you purchase a product through an affiliate link your price will remain the same and The Slow Roasted Italian will automatically receive a small commission. Thank you for supporting us, it helps us keep creating new recipes.


  1. Cannot get to "print" for the onion soup. Every time I click the 'print' option, it goes to a different soup (potato). Very confused.

    1. Holli@TheSlowRoastedItalianJanuary 17, 2018 at 8:41 AM

      Thanks Patte, it is fixed now, Enjoy!

    2. I looked for that print button on the recipe and didn't find it, so I highlighted just the title to the end of instructions, right clicked on the highlighted text and clicked print. and it printed picture and all.

  2. Hi! I can't find Sherry Vinegar near me can you sub sherry wine? or can you think of something else that would work? Thanks!

    1. We used sherry wine today and loved the soup.

    2. Thank you! Trying it tomorrow. Everyone is looking forward to it!

    3. I'm in the middle of making this recipe right now! My house smells Heavenly!!!!

  3. Where are those soup crocks fron!?


If you really like a post, please Facebook and give it a THUMBS UP or Pin It on Pinterest!

We love to hear your comments and hear when you have used a recipe. ❤ ❤ ❤