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Slow Cooker French Onion Soup in bowl with cheee crouton

Slow Cooker French Onion Soup

Janice Pattie
Slow Cooker French Onion Soup is such a simple soup to make, and the ingredients are inexpensive and freely available.  It’s an easy version of the classic French recipe and it’s packed with flavour. Top with a grilled cheese crouton and you have a filling and delicious meal.
5 from 2 votes
Prep Time 10 minutes
Cook Time 5 hours 10 minutes
Total Time 5 hours 20 minutes
Course appetiser, Soup
Cuisine French
Servings 6
Calories 411 kcal

Equipment

  • 1 Slow Cooker
  • 1 Sharp knife or mandoline or food processor with slicing disc
  • 1 chopping board
  • 1 weighing scales
  • 1 Measuring spoons
  • 1 Square of muslin
  • 1 piece of string
  • 1 Air Fryer optional

Ingredients
 

For the Soup

  • 4 large onions
  • 80 grams butter
  • 2 tsp caster sugar superfine sugar
  • 2 tbsp plain flour all purpose flour
  • 2 tsp salt
  • 1 litre beef stock beef broth
  • 1/2 tsp pepper

For the bouquet garni

  • 1 bay leaf
  • 10 grams fresh thyme on the stem
  • 10 grams parsley stalks

For the croutons

  • 6 slices French stick
  • 100 g Gruyere cheese grated

Instructions
 

For the Soup

  • 4 large onions, 80 grams butter
    Put the onions and butter into the slow cooker put on the lid on HIGH and cook for 2 hours.
    French onion soup onions and butter in slow cooker
  • 2 tsp caster sugar
    Add the sugar and mix through the onions. Cook for a further 2 hours.
    French onion soup caramelised onions with wooden spoon
  • 2 tbsp plain flour
    Add the flour and mix the flour into the onions and butter. cook for a further 10 minutes.
    Add flour to French onion soup
  • Make the bouquet garni by placing a sprig of thyme, bay leaf and parsley into a piece of muslin and tie with string.
    Bouquet Garni herbs on muslin
  • 1 litre beef stock, 1/2 tsp pepper, 2 tsp salt
    Add the beef stock, season with the salt and peper and add the bouquet garni. Cook for a further 1 hours.
    Add beef stock to french onion soup in slow cooker
  • Remove the bouquest garni.
    Remove bouquet garni from French onion soup

For the Cheese Croutons

  • 6 slices French stick, 100 g Gruyere cheese
    Cut the bread into four thick slices, top each slice with grated cheese.
    French bread with grated cheese
  • Place under a preheated grill (broiler) and grill until the cheese is melted and bubbling. Alternatively, place the slices of bread into a pre-heated Air Fryer and top with the grated cheese. Cook at 200F for 10 minutes.
    Grilled cheese on french bread
  • Fill the bowls with the piping hot soup and top each with a cheese crouton. Serve immediately.
    Slow Cooker French Onion Soup in bowl with cheee crouton

Nutrition

Calories: 411kcalCarbohydrates: 47gProtein: 17gFat: 18gSaturated Fat: 10gPolyunsaturated Fat: 1gMonounsaturated Fat: 5gTrans Fat: 0.4gCholesterol: 47mgSodium: 1705mgPotassium: 552mgFiber: 4gSugar: 8gVitamin A: 682IUVitamin C: 7mgCalcium: 283mgIron: 5mg