French Onion Soup, Slow Cooker Style

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
  • ยผ 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.