This Slow Cooker French Onion Soup is full of caramelized onions and beefy rich broth that simmers away while you do everything or nothing. Top with toasted baguette and gruyere cheese and you have the most delicious light dinner or appetizer!
We love frenchie food around here! There are several fabulous restaurants in the Seattle area that we frequent and good French Onion Soup is the start to every perfect frenchie meal!
Why cook this soup in the Slow Cooker opposed to stove top? Time. Time for those delicious onions you carmalized to infuse the broth and it’s ready when you are!
What are the best kind of onions to use in French Onion Soup –
- Good old cheap and cheerful yellow onions – Just the way Julia Childs did it in Mastering the Art of French Cooking. If it”s good enough for her, it’s good enough for me! But if you prefer sweet onions you can certainly use them just omit sugar from the recipe. I find them on the mild side and like this soup with big flavored onions.
How to cut onions with no tears! I am one of those people that have a very very strong aversion to onion vapor. It can literally ruin my day. I tried everything from holding my breath to using a table top fan to blow away the vapors!
I finally solved the problem with Onion Goggles. You can see them in the picture below. I swear by them! It’s quite the look, but I’ll take the relief over looks any day!
The picture above is 8 cups of onions. It sounds and looks like so much but it reduces down to the picture below.
Pour those beautiful onions into the slow cooker along with your beef broth, sugar and spices and you are almost done!
What kind of broth do I use for French Onion Soup –
- Julia would brown beef bones and simmer them for hours along with carrots, onions etc. But we are not Julia and as much as I love her I simply don’t have the time or desire to do this. We buy beef broth, low sodium, at our local grocers. Once the onions infuse the broth it becomes rich and flavorful!
Now that your broth has simmered away and your house smells like a French cafe. Line a baking sheet with sliced baguettes and toast under the broiler until brown on both sides. We keep these crunchy so they soften up in the soup.
Ladle your onion soup into sturdy bowls that can take a bit of broiler heat. Top with toasted baguette slices and a big handful of gruyere cheese.
Broil for a minute or two until brown and bubbly.
Serve this delicious soup with additional bread and a simple salad. A light meal or perfect starter!
More Slow Cooker recipes:
Slow Cooker Beef Bourguignon – another classic from Julia Childs Mastering the Art of French Cooking only we developed it for the slow cooker.
Easy and Tender Slow Cooker Pot Roast – a classic dinner everyone loves!
Slow Cooker Bolognese Sauce – a delicious blend of beef and tomatoes simmered for hours for an authentic Italian flavor!
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Slow Cooker French Onion Soup
- 8 cups yellow onion, thinly sliced (about 3 pounds or 6 large onions)
- 4 tablespoons butter
- 2 tablespoons brown sugar omit if using sweet onions
- 3 garlic cloves, minced
- 8 cups beef broth we prefer low sodium
- 2 tablespoons worcestershire sauce
- 1/2 cup dry sherry or dry white wine
- 6 sprigs fresh thyme or 2 teaspoons dried thyme
- 2 bay leaves
- 8 slices french bread, toasted additional bread to serve on the side if desired
- 1 cup grated gruyere cheese
- Melt butter in large skillet over medium heat. Add sliced onions and sugar.
- Cook and stir for about 20 minutes until onions are light in color and fully caramelized.
- Add caramelized onions to slow cooker along with beef broth, garlic, sherry, thyme and bay leaves.
- Cook on low for 5-6 hous and up to 8 hours. Taste for salt. May need to add several pinches if using lower sodium broth
- Remove bay leaves and thyme sprigs and discard.
- Toast sliced baguette under broiler turning once until browned.
- Ladle soup into hearty bowls. Top with a slice of bread and handful of grated cheese covering the entire top of the soup.
- Place soup bowls on large sheet pan (for ease of handling) and broil until top is golden brown and bubbly.
- Serve with additional bread and a simple salad as a light meal or appetizer.
- If using sweet onions, omit sugar
- To cook on stove top: Follow all directions only add to large soup pot and simmer for an hour or two.
- Substitute swiss cheese in a pinch
- Taste for salt especially if using lower sodium broth
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Karen Roman says
Another excellent recipe
Everyone loved how comforting this is! Thanks for the recipe!
What a perfect soup for the fall! I love anything with caramelized onions and this soup looks like it won’t disappoint!!
This is one of my favourite soups. So cheesy and comforting.
I’ve been a chicken when it comes to making french onion soup, but this version is so simple and so delicious, it’s hard to believe I’ve been avoiding it this whole time!
Jessica Formicola says
French onion soup id my absolute favorite, and this recipe is the best I’ve found! Thanks so much for sharing!
Kelli Hoel says
Too funny, I caramelized onions in the instant pot on slow cooker all day yesterday and last night just to make French onion soup (yes, I’m too lazy to monitor them on the stove)! They’re finishing in the cast iron pan to reduce the liquid while we make homemade chicken stock in the pot. Making this today and looking forward to the end result. Miss ya neighbor Rachel!
Gina Saunders says
This looks delicious, and I am SO making this soon. How much beef broth should be used? Thank so much again for another beautiful, easy recipe.
8 cups. ugh. We like the low sodium.