French Onion Soup in the Slow Cooker recipe

Preparation Time: 30 minutes | Cooking Time: 10 hours

This rich, well-flavoured soup is cooked in the slow cooker, giving it a fabulous flavour for very little effort. Just finish the croutons off under the grill before serving.


  • 6 tbsp. butter
  • 4 large onions, peeled, sliced, separated into rings
  • 120ml sherry
  • 1.5 litres beef stock
  • 2 garlic cloves, minced
  • 1 tbsp. brown sugar
  • 1/4 tsp. dried thyme
  • 1 bay leaf
  • Salt and black pepper to taste
  • 8 slices French baguette
  • 60g Gruyere, grated
  • 40g Emmental, grated
  • 20g parmesan, grated
  • 2 tbsp. mozzarella, grated


  1. Melt butter in a large heavy pot. Add the onion, and cook, stirring over a low-medium heat for around 10 minutes or until soft. Sprinkle on the sugar and cook on a medium heat, stirring often, for 30 minutes or until the onions are very soft and brown. Add garlic and fry for 1-2 minutes, then stir in the sherry, scraping any bits off the bottom of the pot, and bring to the boil.

  2. Pour into the slow cooker. Add the beef stock, thyme, bay leaf and a good pinch of salt and black pepper. Cover and cook on high for 4-6 hours or on high for 8-10 hours.

  3. Make the croutons. Mix together the gruyere, emmental, parmesan and mozzarella. Spoon the soup into oven proof ladles and place the baguette slices on top. Evenly sprinkle the cheese over the bread and pop under a hot grill for a few minutes or until the bread is toasted and the cheese melted.

For a spicy, savoury flavour, spread the bagyette slices with Dijon mustard. Recipe serves 4.

Recipe Details:

  • Author: Laura Young.
  • Published:

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