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Give this slow cooker French onion soup recipe a try. It has caramelized onions in a beef broth topped with a crusty bread and cheese – YUM!
Slow Cooker French Onion Soup Recipe
Let me just start by saying: if you like French Onion Soup, you've got to try this Slow Cooker French Onion Soup . . . yummm!
My husband has a favorite restaurant in Colorado Springs that makes some plain-old-fantastic French Onion Soup, and he even agreed that this was almost as good as theirs. If you love french onion soup, you do not want to miss trying this recipe.
🍴 Menu Plan Note: This yummy French Onion Soup recipe can be found in the Slow Cooker Meal Plan: Week 5!
How to make French onion soup from scratch?
The very best onions to use when making French onion soup from scratch are those big, sweet and meaty Vidalia onions. If those aren't in season then large yellow onions are great also.
Slice onions about 1/4-inch thick and sauté in some butter until they are nice and golden in color (being careful not to cook too fast). As you begin cooking the onions, they will eventually take on a beautiful caramelized coloring as they release their sugars.
Next, add some beef broth and seasonings (you can do as simple as salt and pepper) and simmer on low 4-6 hours.
Finally, the best part! Ladle the French onion soup into oven-safe soup bowls. Top each bowl with a slice or two of bread and a good amount of Swiss cheese (to make the cheesy toast on top).
Pop under the broiler for a couple of minutes and be prepared for a dance to occur on your taste buds!
Be sure to let it broil long enough to get those crusty cheese pieces on the side of your bowl. Those are the best, ha! 😍
How to caramelize onions in the slow cooker?
You can caramelize onions on the stove top or in the slow cooker and both are equally delicious!
But, if you want to skip the step of cooking them on the stove top, we recommend a slow cooker with a stovetop cooking option like this one. Just cook directly in the slow cooker like you would a skillet on your stove top. These all in one slow cookers are truly the best. 🙂
Plus, only 1 pan to clean 🙂
The key to wonderful caramelized sweet onions is low and slow. Just add some heat, real butter and lots of time and patience (which is a bit hard for this always..in..a..hurry..momma)!
How do I thicken French onion soup?
Every onion soup needs a thickener so you don't end up with watery onion soup. For this recipe, we use a bit of flour and a packet of Au Jus seasoning mix. It makes for a perfect combination and the Au Jus adds a depth of flavor to the broth that is just divine.
What goes with French onion soup?
Even though there is bread right in the soup, hmmmm, I love to serve even more bread when I make it. You can use the rest of the French bread loaf or bake up a batch of my favorite homemade bread. Of course, I serve salad with just about everything so a nice full salad would be a perfect addition.
Of course you can serve this Slow Cooker French Onion Soup as an appetizer. If you decide to go that way, here are a few recipes I think this would be a perfect starter for.
- Grilled Flat Iron Steak with Gourmet Butter
- Grandma's Beef Brisket
- Low Country Boil on the Grill
- Slow Cooker Brown Sugar Pork Tenderloin with Balsamic Glaze
While serving this meatless meal will help you pinch a few extra pennies at the grocery store, I promise you'll be plenty stuffed when you finish this one . . . that cheesy gooeyness couldn't be one bit better.
Slow Cooker French Onion Soup
- slow cooker
- 4 Tbsps butter
- 6-8 large yellow onions, sliced
- 3 cloves garlic, minced
- 3 Tbsps flour
- 1 Tbsp Worcestershire sauce
- 1 tsp sugar
- 2 32 oz cartons low-sodium beef broth
- 1 oz pkg Au Jus seasoning mix
- 1 loaf French bread, cut into 1-inch thick slices
- Swiss cheese slices
- In a large skillet, melt butter; add sliced onions. Sauté until onions are translucent and start to caramelize; add garlic.
- Transfer onion mixture to slow cooker.
- Mix together flour, Worcestershire, sugar, 1 teaspoon salt and 1/4 teaspoon pepper.
- Pour broth, Au Jus mix and Worcestershire mixture into slow cooker, stirring to remove any lumps from the flour.
- Cover and cook on low 4-6 hours.
- Pour soup into oven-proof bowls. Place on a baking sheet, and put a piece of sliced bread on top of soup. Cover with cheese, and broil in oven 2-3 minutes, until cheese is bubbly.
Looking for more yummy meals? This recipe is from week five of our slow cooker menu plans, including this meal + 59 other AMAZING recipes (and 12 desserts too)! You'll also get lifetime membership in our private Facebook group, full of other families encouraging one another to make dinner each night together too.
These are the BEST MENU PLANS on the planet (and, the only menu plan that ship all the grocery lists, menu plans and recipe cards right out to you ~ no downloading or hunting down recipes on your phone at dinnertime ever again!) Go HERE to learn more. I know you're going to love these!
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Would this work with vegetable broth to make a vegetarian version or so you think it would change the flavor too much?
Can you freeze this onion soup?
Yes- I think that would totally work!!!
Just had surgery yesterday and my hubby is making this as we speak!! French onion is one of my favorite soups!!
Nora Rodriguez says
Ok I have to ask what is the name of the restaurant your husband likes in Colorado Springs??? We live in Colorado Springs and love this restaurants just for their French onion soup. We made their tonight and LOVE it!
It’s been 25 years since we went on our anniversary – I have no idea which one it was (but it was soooo good – a friend of his had recommended it!) If you find an awesome restaurant there let us know (I’d sure love to go back!) My husband did say it was in the Old Town part of Colorado Springs- but that’s all he remembers!
I love this recipe! I also love the soup bowls in the video-if you don’t mind sharing, would you please let me know where you found them (or the manufacturer)? Thank you
They’re old Bybee Kentucky bowls – they no longer make them (but I love them!)
Barbara Quinn says
I love to marinate stakes in onion soup before putting it on the grill. There is nothing like it!
Donna Aldridge says
You often include some kind of a packaged mix in your recipes. I never use them. I could blow up the photo to see you got it at Krogers. Plz indicate source of package mixes.
I used a small packet of Au Jus mix from Kroger (have also used McCormick Brand but Kroger brand works too), and then small bouillon cubes as well. Hope that helps Donna!
Susan Hayes says
Nvrmnd Looked at someone's other post Got it Thanks..
Sorry about that Susan – glad you found it!
Susan Hayes says
Your Recipe Does not tell you what to do with the Au Jus and then in step 4. to mix pepper which your ingredients do not have the amount stated for Pepper just an FYI..
Lisa Bliss says
I usually make this on top of the stove, but this sounds so good and saves so much time!! Thank you so much for posting!
It’s so easy – and I’m all about using my slow cooker when I can! 🙂
As I live in Colorado Springs, I’m curious which restaurant serves the delicious soup!!
It’s up above in another post to someone.
I am a big fan of FRENCH Onion Soup but, PLEASE, skip the Swiss cheese! You must use Gruyere (But very expensive and sometimes hard to find) or substitute with Mozzarella (or half of esch)! I never leave Paris without enjoying French Onion Soup at least once! (Been there over a dozen times, partly bc we lived in Europe for awhile so not meant to be a brag!). I DO like your idea of adding a bit of thickner to the soup.
Im in the middle of making this, but the recipe doesn’t say what to do with the Au jus mix, or how much pepper to use. 🙁
I’m so sorry Erica! It should say 1/4 tsp pepper. Also, add the Au Jus mix in with the flour, Worcestershire sugar and pepper. Hope that helps! (And thank you for letting me know!!!)