French Onion Soup, Slow Cooker Style

Slow Cooker French Onion Soup cropped.jpg

Pull that slow cooker out of the cabinet and put it to work with this delicious French Onion Soup. Make meltingly sweet (hands-off) caramelized onions and add grated cheese to the final dish for a great take on this well-loved classic.

Prep:  10 minutes
Cook: 10 minutes
Yield: 6 Servings


  • 8 cups sliced onions  (6-7 large onions or 3 lbs)
  • 2 Tablespoons unsalted butter, melted
  • 2 teaspoons kosher salt
  • 2 tsp minced garlic
  • 1/4 cup dry (fino) sherry
  • 5 sprigs fresh thyme
  • 1 bay leaf
  • 3 cups low sodium chicken stock
  • 3 cups low sodium beef stock
  • 1 teaspoon sugar
  • 1 tsp reduced sodium soy sauce
  • ¼ tsp black pepper


Combine onions, butter, and salt in a slow cooker.  Cook on high for 8-10 hours on low or until onions are well browned.  Add sherry and stir to combine.  Continue to cook on high with lid off for 10-15 minutes to evaporate alcohol.  Add herbs, both stocks, and sugar to onions, combine well, and cook, covered, on high, for 2-3 hours to marry flavors. Discard herbs. Stir in sugar, soy sauce, and black pepper.  Soup may be made up to 3 days before serving.


Serve this soup with optional grated mozzarella and parmesan cheese.