Clean and cook cauliflower as. Drain well and force through a fine sieve. Beat in well-beaten egg yolks and 4 tablespoons softened butter, and season to taste with salt, freshly ground black pepper and freshly grated nutmeg. Pour into a well-buttered soufflé dish or charlotte mould, and cook in a pan of hot water in a moderate oven (375°-M4) for 25 minutes. Turn out on to a heated serving dish and mask with Hollandaise Sauce.