Slow Cooker French Onion Soup

Recipe for Slow Cooker French Onion Soup
Becky Luigart-Stayner


1/2 cup (1 stick) butter or margarine
3 large onions, thinly sliced
4 cups hot water
2 tablespoons instant beef bouillon or 6 beef bouillon cubes
1 teaspoon Worcestershire sauce
1/2 teaspoon salt
4 slices toasted French bread
1/2 cup freshly grated Parmesan or Gruyere cheese


Melt butter in a skillet over low heat. Add onions and cook slowly, up to 45 minutes to release maximum flavor, or until nicely browned, stirring frequently. Transfer to a slow cooker. Add water, bouillon, Worcestershire sauce, and salt. Cover and cook on low for 4 to 6 hours.

To serve, top each bowl with 1 slice of bread. Sprinkle each with 2 tablespoons Parmesan. Recipe may be doubled and kept hot in slow cooker.


Makes 4 servings.

Reader Comments

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French Onion Soup

I always use home made beef broth from beef short ribs or prime rib bones, and I add wine to the onions plus Brandy or cognac for incredible flavor. Always use Gruyere cheese and a tip, I often put the bowls in a deep roasting pan as it's easier to get them out of the hot oven after broiling the cheese.


Toast the bread first and melt some of the cheese on it before topping bowls.

Sherry in onion soup

I thought there was Sherry in onion soup. Is that not right?


To answer Ron's question (and, frankly, mine as well) I did some research. According to the Epicurious website, and I find them a VERY reliable source for anything relating to cooking, they experimented with red, yellow, and Vidalia onions. They found that the Vidalias, cooked low and slow with a sprinkle of salt and sugar for caramelizing, was the best choice for a sweet, nutty and silky result. I hope that this helps.

Question about French Onion Soup

Thanks for the recipe and wine suggestions from the comment. Pairing the soup with the right wine in your glass also enhances the flavors.
I was wondering, what is the best type of onion to use for onion soup?

French Onion Soup

We use some Brewer's Yeast, and yes a good splash of Old Vine Zinfandel with the onions to deepen and enhance flavor. Home made Beef stock is the best and yes make sure it's Gruyere. Go BIG flavor, or go home. . .

French onion soup

If it doesn’t have wine it’s not French onion soup thank you

Crockpot French Onion Soup

I used BOXED beef broth (consume) rather than the bouillon (which makes it rather too salty in my opinion) and think it would be even better with homemade beef broth. Plus it has to be Gruyere cheese - it's the right flavor and melting point. It's a nice idea, making it in the crock pot, the recipe just needs a little tweaking. jh

French onion soup

Absolutely Gruyere cheese. Sure it's more expensive, but it's worth it. It puts "French" in French onion soup.