Angel Food Cake - Chocolate Orange

The lightness of angel food cake with an intense chocolate orange flavour, and a little bit of texture from the chocolate chips. Fantastic with chocolate sauce.

1. 1

   You will need a small American style 'tube pan' cake tin (7 inch / 18 cm) or a round, deep sided, loose bottomed cake tin of the same size*. Unusually, you don't need to grease or line the tin, and need to use one that is not non-stick.
   
   Preheat the oven to 180 degrees C.
   Sift the flour, corn flour and 20 g of the sugar into a bowl and repeat 3 times.
   Blitz the chocolate in a mini chopper or coarsely grate with a cheese grater. Finely grate the orange zest.
   In a stand mixer, or a large bowl with an electric hand-whisk, whisk the egg whites until frothy and add the lemon juice and cream of tartar. Increase the speed to high and whisk until white and just beginning to form very soft peaks, then add the remaining sugar a third at a time and whisk until the peaks are firmer, but the mixture is still soft and cloud-like, and not dry. Add the vanilla towards the end.
   Fold in the vanilla extract and orange zest, then sift in 1/3 of the reserved flour, cornflour and sugar mixture and very carefully fold in, using a rubber spatula or a large metal spoon. Next carefully fold in 1/3 of the finely chopped / grated chocolate. Repeat twice more to use up all the ingredients.
   Spoon into the tin (it should fill almost to the top, leaving about 1cm, and no more than 2cm). Bake for 30 - 35 minutes until golden on top, and a skewer comes out clean (except for maybe a bit of melted chocolate).
   Remove from the oven and immediately turn upside down on a wire rack, propping up if needed, and if your 'tube pan' doesn't have little 'feet'. (Some people suggest putting the tube over the neck of the bottle). The cake won't fall out, as it will be stuck to the tin, but this stops it from deflating.
   Leave to cool completely, then run a metal palette knife around the tin and push the bottom to release the cake.
   Serve plain, dusted with icing sugar and / or cocoa, or with a simple chocolate chocolate sauce, cream or ice cream**, and / or orange segments.
   The best knife to use when cutting the cake is a serrated one, e.g. a bread knife.
   
   Simple chocolate sauce using the remaining 40g chocolate*** :
   Break the chocolate into pieces and put it in a small saucepan with the sugar and water over a medium heat and stir until the chocolate had melted the sugar has dissolved and it is starting to bubble. Turn down the heat and simmer for about 5 or 6 minutes, stirring often, until a little thicker and syrupy. Pour over the whole cake, or serve in a jug, warm / cool, to pour / spoon on individual slices.