• Line and grease a 23 x 30 cm/9 x 12 inch Swiss roll tin. Whisk the eggs and sugar until pale and very thick.
• Fold in the cocoa and flour with a metal spoon, then pour the mixture into the tin. Bake in a hot oven for 7 - 10 minutes.
• Place a clean tea-towel on a work surface, cover with greaseproof paper and sprinkle with caster sugar. Turn the Swiss roll out on to the paper. Trim off the crusty edges and lay a sheet of greaseproof paper on top.
• Roll up tightly to enclose the paper. Cool.
• Beat the butter or margarine and icing sugar until pale. Melt the chocolate in a basin over a saucepan of hot water and add it to the mixture. Unroll the cake, remove paper and spread with some buttercream. Roll up and cover with the remaining buttercream. Decorate as shown.

Freezer Tip

• Open freeze the cake until firm then place in a polythene box. Remove from box and defrost at room temperature.