Cook basmati rice, leave to cool. Heat oven to 160C/140C fan/gas 3. Grease a large ovenproof dish with some of the butter. Push the egg yolks through a sieve and roughly chop the whites.
Gently heat the cream in a frying pan until just below boiling point, then add the fish. Cover and poach for 4 mins. Place the wine in a pan with the saffron and warm to infuse. In a large bowl, mix together the rice, cayenne, curry powder, nutmeg, seasoning, chopped egg whites and saffron-infused wine. Lift the fish out of the cream and flake into the bowl - removing any bones as you find them. Scrape in the cream and gently mix together once more.
Tip everything into the buttered dish and dot the top with the remaining butter. Bake to heat through for 20 mins, then serve scattered with the parsley and sieved egg yolk, with lemon wedges on the side.