See Sauce Nantua recipe. Puree the fish, making sure to scrape down the sides of the food processor to insure good results. Add the egg white and blend for 30 seconds, then add half of the cream and process for another 30 seconds. Remove this mixture to a mixing bowl over ice and beat in cream with a wooden spoon until light. Season with salt, pepper, nutmeg and red pepper. Pour the prepared mixture into small individual dishes or custard cups. Place dishes in a pan and add water halfway to the rims. Cook in a 180ºC oven for about 15 minutes or until the mousseline is firm to the touch. Unmold and top with Sauce Nantua. Note: It's difficult to know how much seasoning to put in to this dish so I suggest you cook one of the dishes first taste it and then adjust the seasonings.