Photo of Slow cooker French onion soup by WW

Slow cooker French onion soup

Total Time
13 hr 35 min
20 min
13 hr 15 min
When the nights are longer and colder weather sets in, French onion soup is the perfect make-ahead staple. The key to the deep rich flavor or this famous soup is caramelized onions. Using the slow cooker, the once long hands-on process fo getting the sugars in the onion to caramelize is not totally hands-free. The first cooking of the onions can be done overnight and results in perfectly prepared onions, ready for soup. When the soup is finished cooking, the slow cooker can be set to warm until you are ready to eat. Cool and store leftovers in the refrigerator up to 3 days or freeze for 3 months. Serve as an appetizer for dinner parties or as a main-dish soup with a side of roasted asparagus sprinkled with a bit of crisped prosciutto.



3 pound(s), sliced (about 6 to 7 large onions)

Unsalted butter

2 Tbsp, melted

Kosher salt

2 tsp

Fino sherry

¼ cup(s)

Jarred minced garlic

2 tsp

Reduced sodium chicken broth

3 cup(s)

Reduced sodium beef broth

3 cup(s)

Fresh thyme

5 sprig(s), (plus extra for garnish)

Bay leaf

1 leaf/leaves


1 tsp

Low sodium soy sauce

1 tsp

Black pepper

¼ tsp, freshly ground

Shredded parmesan cheese

3 Tbsp


  1. Combine onions, butter and salt in a slow cooker; cover and cook on high until onions are well-browned, about 8 to 10 hours. Add sherry and garlic; stir to combine. Leave slow cooker set to high and let sit, uncovered, for alcohol to burn off, about 10 to 15 minutes.
  2. Stir in both broths, thyme, bay leaf and sugar; cook, covered, on high, for flavors to blend, about 2 to 3 more hours. Remove thyme and bay leaf; stir in soy sauce and pepper. Sprinkle each serving with cheese and garnish with thyme just before serving. Yields about 1 1/2 cups soup and 1/2 tablespoon cheese per serving.


Soup may be made up to 3 days before serving.