Slow Cooker French Onion Soup

Slow Cooker French Onion Soup

Even though it's only the beginning of September, I've already been cranking out the soup recipes.  In particular, the slow cooker soups.  You just can't go wrong with a big pot of soup waiting for you at the end of the day, can you?!

Since I caught a little end-of-the-summer cold this past weekend, I've been especially craving hot comfort food.  Which brings us to: Slow Cooker French Onion Soup!

While I already have a delicious recipe for French Onion Soup on here, it’s one that requires a lot of hands-on time.  The onions are slowly cooked in the oven for over two hours and then the soup takes another hour to cook on the stovetop.  That’s a lot of time hanging around the kitchen and while it’s true that French Onion Soup takes some time to develop flavors (and that recipe is completely worth it) I wanted to come up with a method in the slow cooker that was less hands on.

Slow Cooker French Onion Soup

This recipe actually requires more time overall, but it’s far less work, as you let the slow cooker do it all for you.  To begin with, you caramelize the onions in your slow cooker overnight.  Did you know your slow cooker can do that for you?!

You simply put your onions, some butter, and salt in the slow cooker and let it go all night long on low.  When you wake up your kitchen will not only smell lovely, but you’ll have deep brown caramelized onions.

After the onions are caramelized, you add the remaining ingredients of the soup and let it cook all day.  Easy, right?!

Slow Cooker French Onion Soup

To top it off, I think the bread and cheese is crucial for French onion soup.  While I’ve used many recipes that simply put the bread and cheese on top and broil it, this recipe actually bakes it for 20 minutes and then broils it.  This allowed the bread to really meld into the soup, and there wasn’t one bit of the bread that hadn’t soaked up the delicious broth.

Can I just say this soup got me the slightest bit excited for chilly weather?!  I love a good hot day but after having this French onion soup, I’m craving a chill in the air.

Slow Cooker French Onion Soup

Slow Cooker French Onion Soup

Print Rate
Cook Time: 16 hours
Total Time: 16 hours
Servings: 6 servings


  • 3 lbs white onions sliced
  • 8 tablespoons unsalted butter
  • 1 teaspoon salt
  • 8 cups beef broth
  • 1 tablespoon Worcestershire
  • ¼ cup white wine or white cooking wine
  • 1 tablespoon red wine vinegar
  • 4 sprigs thyme plus additional thyme for topping
  • Loaf of Italian bread cut into ¾” slices, for topping
  • 2 cups shredded Gruyere cheese


The night before (ideally):

  • Place onions, butter, and salt in large slow cooker.
  • Cook on low for 8-10 hours. This works best if you do it overnight.
  • In the morning, add beef broth, Worcestershire, wine, red wine vinegar, and thyme.
  • Season with salt and pepper, to taste.
  • Cover and cook on low for another 6-8 hours.
  • After 6-8 hours, preheat oven to 350 degrees F. Place oven proof bowls onto baking sheet.
  • Ladle soup into oven proof bowls.
  • Top with 1-2 slices of bread and top each bowl with ~? cup of shredded cheese.
  • Bake in preheated oven for 20 minutes.
  • Turn on broiler and broil until golden brown, keeping a very close eye on it.
  • Garnish with additional thyme leaves.
  • Enjoy!
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Slow Cooker French Onion Soup

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  1. I can't WAIT for soup season! Portland, OR is still a billion degrees out, and the nearby fire isn't helping, but once our state finally sees some rain again, I'm making this soup, stat!