Slow Cooker French Onion Soup

Slow cooker french onion soup

French onion soup requires a great deal of patience. My first experience making it ended with the bitter, burnt flavor of impatient onion cooking. It takes time to caramelize the sugars in onions. The rich, deep brown color and sweet scent of properly caramelized onions is divine. The slow cooker is perfect for this job. Run it overnight and you'll wake up to perfectly caramelized onions. You can make this soup several days in advance. The flavor actually gets better if you let it sit for a day or two in the fridge.


All Ingredients

½ cup (112g) butter
8 (1080g) onion, sliced 5 minutes
4 sprigs (6g) thyme
1 tsp (4g) all-purpose flour
3 cups (708g) vegetable stock, no to low sodium
1 tsp (6g) salt
4 slices (72g) baguette
8 slices (170g) Comte cheese
¼ cup (17g) Gruyere cheese, shredded


  1. Melt the butter in the slow cooker and coat the inside of the slow cooker with butter. 1 minute
  2. Add the sliced onions and 2 sprigs of thyme to the slow cooker and set overnight up to 24 hours on low heat. Be sure that the sliced onions are uniformly sliced so that the onions caramelize evenly. 1 day
  3. On the next day, you should have perfectly caramelized onions, ready for your onion soup. Transfer to a medium saucepan on medium heat. 3 minutes
  4. Add flour to the onions and stir thoroughly until a paste has formed. 1 minute
  5. Gradually add the vegetable stock and bring to a boil. Add salt to taste. Depending on your stock, you may need to add less salt. 1 minute
  6. Add the remaining thyme and simmer for 7 to 10 minutes. 10 minutes
  7. While the soup is simmering, toast the baguette slices. Preheat your broiler on high. 1 minute
  8. When the soup is ready, ladle the soup into 4 heat proof serving bowls with a narrow opening. Float a slice of baguette on top of each bowl of soup and top with cheese -- 2 slices of Comte and 1 tbsp of Gruyere on top of each bowl. 1 minute
  9. Place the bowls on a baking tray to catch any dripping soup or cheese and place under the broiler for 1-2 minutes. 2 minutes
  10. Enjoy immediately!
Slow cooker french onion soup ndata