1. Preheat oven to 425 F

2. Grease a 13"x9" Swiss roll tin.

3. Cut a piece of baking parchment a few centimeters large than the tin on all sides; place into tin, creasing to fit sides. Cut corners and fold to fit snugly.

4. Put eggs and sugar in a large bowl and stand over hot water.

5. Whisk until thick, pale, and creamy- about 5 minutes.

6. Remove from bowl of water; continue to whisk 3 minutes more or until mixture is thickened enough to leave a trail with a spoon.

7. Sift flour and 2 tbsp cocoa powder onto a sheet of greaseproof paper; sift again into the creamy mixture.

8. Add hot water; fold mixture together with a metal spoon.

9. Pour mixture into prepared tin; tilt tin back and forward to spread evenly.

10. Bake for 8-10 minutes or until well risen and just firm to the touch.

11. Place a sheet of greaseproof paper on a clean, damp tea towel.

12. Turn out the cooked sponge on to the paper; cut off crusts.

13. Cover with another sheet of greaseproof paper; roll up cake from a short side with paper inside.

14. Wrap in a tea towel and allow to cool.

15. Place 3 oz softened butter into a bowl.

16. Sift 6 oz icing sugar into the butter, beating well between additions until smooth and creamy.

17. Dissolve cocoa powder in boiled water while hot; allow to cool.

18. Stir chocolate liquid into butter and sugar mixture and beat to a spreadable consistency.

19. Carefully unroll cool sponge; discard paper.

20. Spread with chocolate buttercream.

21. Spread with conserve or jelly.

22. Roll up sponge again; dust top with 1 tbsp icing sugar and 1 tsp cocoa powder.

23. Slice to serve.