6 tbsp bitter marmalade, warmed in a pan and sieved
Put 3 layers of clingfilm on top of each other. Tip the ice cream out of the tub on its side then wrap in the clingfilm. Quickly squish and mould the ice cream into a fat cylinder about 5-6cm in diameter then put back into the freezer.
Line a Swiss roll tin approx 23x32cm with baking parchment. Heat the oven to 190C/fan 170C/gas 5. Put the sugar and eggs into a bowl then whisk with electric beaters until pale and thick (it will take a little while). Take 3 tbsp flour from the full amount and replace with the cocoa. Sift flour and cocoa over the egg mix then gently fold in. Tip the mix into the tin, level out, and bake for 12 minutes.
Cover another sheet of baking parchment with a dusting of cocoa. Tip the sponge out of the tin onto the cocoa, peel away the parchment and drizzle over the booze, loosely roll and leave until just lukewarm. Unroll and spread the marmalade over the Swiss roll. Take the ice cream cylinder from the freezer and remove the clingfilm. Wrap the sponge around the ice cream, trimming so you have a smooth join. Trim the ends off.
Wrap in baking parchment and put back in the freezer for an hour or until you need to serve it. Leave out of the freezer for 10 minutes before slicing.