Melt 175 g of the butter in a frying pan over low heat. Stir in the prawns, cayenne pepper, nutmeg and lemon juice and cook gently for a few minutes just until the prawns turn pink. Take care not to overcook the prawns. Divide the mixture among four 1-cup ramekins and chill for 30 minutes.
Melt the remaining butter over very low heat, leave to stand until cooled, then pour through a small sieve lined with muslin, taking care not to pour in the white ‘solids’ from the bottom of the pan. Spoon the butter over each dish of potted prawns to cover completely. Return to the fridge and chill for a further 30 minutes, or until the butter has set. Serve with warm, crusty bread or toast.
Potted Fish: Other seafood can be potted by this method. Especially good are smoked fish such as mackerel, trout or salmon. Keep to the same quantity – that is, 250 g prepared fish to 250 g butter. Flake the fish fairly coarsely and remove any bones. You may like to increase the amount of lemon juice when using an oily fish such as mackerel or salmon.