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Slow cooker french onion soup in bowl with two slices of toast covered in cheese

Slow-Cooker French Onion Soup

Deborah
Full of flavour beefy broth, super tender caramelised onions and oozy cheesy toast on top...just perfect!  
Prep Time 20 minutes
Cook Time 6 hours 25 minutes
Total Time 6 hours 45 minutes
Course Soup, Starter
Cuisine French
Servings 6 to 8 people

Ingredients
  

  • 1kg onions finely sliced
  • 45g butter
  • 30g brown sugar (I use soft light brown)
  • 1.8l beef stock (made with stock cubes or pots)
  • 1 tbsp Worcestershire sauce
  • 1 clove garlic crushed
  • 75ml marsala (see Notes)
  • 4 sprigs fresh thyme, or 1 tsp dried thyme
  • 1 bay leaf
  • slices of French baguette or bloomer bread (they need to be thickly sliced!)
  • 150g g gruyere cheese grated

Instructions
 

  • In a large frying pan, cook the onions, butter and brown sugar over a medium to low heat for about 20 minutes until golden and caramelised.
  • Once golden, add to them to the slow-cooker along with the remaining ingredients except the bread and cheese.
  • Cook on low for 6 to 8 hours (I find 6 hours is enough). Heat the grill to high about 5 minutes before the end of the soup cooking time.
  • Grill one side of each slice of bread until lightly golden. Remove and discard the bay leaf and thyme sprigs from the soup, then ladle it into bowls. Place bread on the soup (you might need to cut the slices of bread in halves depending on what kind you use), toasted side onto the soup, then top with grated cheese.   Place the bowls onto a baking tray and then grill for 2 to 3 minutes or until cheese is melted and browned.   Enjoy...with some extra oozy cheesy toast on the side...if you fancy!

Notes

  • Marsala – the original recipe uses dry sherry, however, I didn’t have any (I thought I did…!), so I checked online what I could use as a substitute.   The options I found were brandy, dry vermouth, port, madeira or marsala.   I’ve used marsala in pate before, so decided I’d give it a try in this recipe…it’s adds a lovely flavour.
  • Any leftovers can be stored in an airtight container in the fridge for a few days and eaten another day.
  • This slow-cooker French onion soup recipe is easily halved if you’re cooking for less people.

 

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Keyword caramelised onions, comfort food, slow cooker, soup