Mix together the eggs, cream and nutmeg in a bowl. Season well with salt and pepper and add the parmesan, crab and lobster meat.
Fry the spring onions in butter in a frying pan and spoon into the case. Spoon the lobster and crab mixture into the prepared flan case and bake for approximately 40 minutes, or until wobbly in the centre.
Remove from the oven and leave to cool. Serve in slices.