Prawn thermidor with watercress and blood orange salad

By Matt Tebbutt From Saturday Kitchen Ingredients For the prawn thermidor 6 large raw tiger prawns in shells, cut in half lengthways and deveined 25g/1oz salted butter 1 shallot, finely chopped 100ml/3½fl oz white wine 450ml/16fl oz fish stock 200ml/7fl oz double cream 1 …