Slow-cooker French onion soup recipe

Method

1. Preheat a 2ltr (or larger) slow-cooker for 5 mins. Add 800g thinly sliced onions, 50g unsalted butter, 2 tbsp caster sugar, 10g thyme sprigs and a bay leaf; stir, then cover and cook on high for 3 hrs (stirring every 1 hr, if possible) until the onions are soft and golden.
2. Stir in 1 tbsp plain flour, then pour in 1.4ltrs beef stock (made with 2 stock cubes), 2 tbsp balsamic vinegar and 3 tbsp Worcestershire sauce. Cover and cook for a further 1 hr.
3. Preheat the grill to high. Cut ¼ white baton into 4 thin slices and grill on a foil-lined rack on both sides until golden. Divide 75g finely grated Cheddar between the toasts, then grill again for 30 secs-1 min until golden and bubbling. Ladle the soup into warm serving bowls and top each with a warm cheese crouton.

• Tip: Make this vegetarian by swapping in vegetable stock and using 1-2 tbsp soy sauce instead of Worcestershire sauce.

• See more Soup recipes

• Tip

  Keep in an airtight container in the fridge for up to 3 days, or freeze for up to 1 month.

• Freezing and defrosting guidelines

  In order to enjoy optimum flavour and quality, frozen items are best used within 3 months of their freezing date. For more tips on freezing and defrosting food, read our article Love Your Freezer.