Stir the raspberry purée over a low heat and whisk in the cornflour. Allow it to cook for 5 minutes then take off the heat and set to one side. Beat the egg whites until they are stiff, adding the sugar. Grease a soufflé mould with butter and dust it with sugar then put it into the fridge.
Mix 1/3 of the beaten eggs with the raspberry purée. Add the rest of the egg whites until you get an even colour. Pour it into the mould and put it in the fridge. Preheat the oven to 180°C and bake for 11 minutes. While it is baking, heat the cream, melting the chocolate into it. To serve, cover the soufflés with icing sugar and accompany them with white chocolate sauce and ice cream.