Gradually add the sugar until mixture is thick and creamy.
Sieve the flour, cocoa and baking powder.
Fold into the mixture.
Pour onto lined flat baking tray.
Bake 6-8 minute at 200C
Turn cake out onto a sugared tea towel, trim edges and roll up. When cool, unroll gently and spread jam and then whipped cream filling and roll up again firmly.
