1

Peel and devein prawns, reserving shells and heads. Rinse prawn heads under water to remove any brain matter. Place peeled prawns in a bowl. Cover and place in fridge until required.

2

Heat oil in a deep non-stick frying pan over medium-high heat. Cook onion, carrot and leek, stirring, for 5 minutes or until onion has softened. Add garlic and reserved prawn shells and heads and cook, stirring, for 2–3 minutes or until prawn shells just change colour. Add wine and bring to the boil. Transfer mixture to a 4.5 litre (18-cup) slow cooker.

3

Add stock, tomato paste, bay leaf, thyme, tomatoes and 1 cup (250ml) water. Cook, covered, on low for 6 hours (or high for 3 hours).

4

Strain soup through a muslin-lined sieve or colander into a large heatproof bowl. Discard shells, heads and other solids. Return broth to cooker. Combine melted spread and flour in a small bowl to make a smooth paste. Stir flour mixture into broth. Cook, covered, on high, stirring occasionally, for 15 minutes or until broth slightly thickens. Season with salt and pepper.

5

Add cream and peeled prawns and cook, covered, on high for 5 minutes or until prawns are just cooked through. Serve bisque topped with dill.