Pick through the crabmeat to make sure there are no pieces of shell remaining.
Place 120g of the butter in a microwave-safe dish and melt in a microwave.
Stir in the nutmeg, cayenne, lemon juice and half of the zest. Set aside for 15 minutes.
Stir the crabmeat into the flavoured butter and season with a pinch of salt and plenty of black pepper.
Divide the mixture equally amongst six ramekins. Cover and place in the fridge for about an hour until firm.
Heat the remaining butter just enough to melt it and stir in the remaining lemon zest. Pour over the surface of the potted crab to cover and seal it completely. Top each portion with a bay leaf, then cover and return to the fridge for 24 hours.
Serve with toasted slices of baguette or sourdough bread.