This classic French Onion Soup in the slow cooker is a game changer. Sweet caramelized onions in a rich beef broth topped with a crusty bread crouton and ooey gooey cheese is hard to resist!
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.
🍴 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). They will eventually take on a beautiful caramelized coloring as they release their sugars. Next, add some beef broth and seasonings and simmer on low 4-6 hours.
Finally, the best part! Ladle the French onion soup into oven-safe bowls. Top each bowl with a slice or two of bread and a good amount of Swiss cheese. 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, oh yeah!
The key to wonderful caramelized 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.
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