Chocolate sponge
Mix the icing sugar with the soft butter until it emulsifies. Add the melted chocolate (45ºC). Then add the egg yolks and mix until smooth. Beat egg whites with sugar until smooth, shiny. Add the whipped egg whites to the chocolate mixture, then the sifted flour. Spread the sponge on a baking sheet with silicone paper and bake at 180ºC for about 20 minutes. Cool down and freeze.