Crockpot French onion soup has all of the flavor of your favorite bistro. Make it at home with fresh ingredients for a fraction of the cost.
This slow cooker soup recipe is ridiculously easy to put together. Not only is it rich and flavorful, but you can top it with as much cheese as you want!
However, it does take quite a bit of time to make so be sure to start early in the morning or even the night before.
If you love the rich flavors in this recipe, try combining them with gooey baked mac and cheese!
Crockpot French Onion Soup
- Onions – While the sweet ones are preferred, you can get away with any “white” variation.
- Sugar – I prefer brown sugar since it adds to the caramel flavor. Start with a smaller amount and add more to taste if you prefer the dish to be sweeter.
- Flavoring – Adding the sherry and Worcestershire sauce to the vegetables creates a deeper flavor, but you can stir them in with the beef stock instead. Also, the thyme and bay leaves can be omitted if you don’t have any on hand.
- Cheese – Shred this yourself, since bagged shreds don’t melt as smoothly. Asiago is a great substitute for Gruyere, or use a blend of both.
Get Free Recipes Sent to Your Email
FAQ – Common Recipe Questions
Want to reduce the cooking time?
Brown the veggies on the stove instead! Place them over low heat for about 1 ½ to 2 hours and add a little extra liquid as needed.
Once they are tender and caramelized, transfer them to the crock pot along with any juice from the pan.
Is 4 hours on High the same as 8 hours on Low?
Crockpots actually cook food at a consistent heat. The High and Low settings just determine how quickly it reaches that temperature.
So, directions that list a certain amount of time on Low can typically be reduced by half when using High instead.
Although most dishes can be prepared on either setting, certain things like roasts and stews do better with a longer time on Low. The flavors become more developed, and the meat comes out more tender.
Do you need to saute onions before slow cooking?
Usually, you can toss them in raw and let them cook with the rest of the ingredients, but they won’t get that delicious caramelized flavor.
Starting them on the stove takes longer up front, or you can prepare them by themselves in the crockpot first. It just depends on how much time you have and how many dishes you want to wash!
With love from our simple kitchen to yours.
Crockpot French Onion Soup + Video
- 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
- 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.
All nutritional information is based on third party calculations and is only an estimate. Each recipe’s nutritional value will vary depending on the ingredients used, measuring methods, and portion sizes.
Originally published January 2018, updated and republished February 2021
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.