Melt the butter and add the rest of the ingredients to it except the crab claws, these tip into a casserole dish, season and spoon the butter mixture over the top (this can be done 2-3 hours in advance.
When serving, preheat an oven to 180deg, put the crab in the oven for 8 minutes. They should not be piping hot!
Serve with crusty bread to mop up the juices.