1 tsp baking powder
225g/8oz caster sugar
4 tbsp cocoa powder, sifted
cocoa powder, for dusting
3 tbsp icing sugar, sifted
225g/8oz self-raising flour
1 tsp vanilla extract
100²µ/3½´Ç³ú dark chocolate chips
4 large free-range eggs
225g/8oz baking spread, straight from the fridge, plus extra for greasing
250g/9oz full-fat mascarpone