We had a little bit of fun with this photo by first dredging with icing sugar and then with cocoa. Tim then scraped some shavings from a block of chocolate.

1. Preheat the oven to 160˚C fan oven/180˚C/gas 5. Line a swiss roll tin with greaseproof paper and then lightly oil the paper.
2. Melt the chocolate in a bowl over a pan of simmering water.
3. Beat together the egg yolks and sugar until they are pale in colour and light and fluffy.
4. Add the hot water to the melted chocolate and pour it into the eggs and gently mix.
5. Beat the egg whites with clean beaters until they form stiff peaks. Gently fold into the chocolate mixture. Pour into the swiss roll tin and gently spread out.
6. Bake in the oven for 20 minutes.
7. Prepare a sheet of greaseproof paper on a work surface and sprinkle about 2 tablespoons of caster sugar over it. Once the cake is cooked, gently turn out onto the paper, leaving the original greaseproof on. Cover with a damp tea towel and leave until it is completely cool.
8. Remove the tea towel and the original greaseproof paper. Beat the cream until it forms soft peaks and then spread over the cake evenly. Use the greaseproof paper underneath to grip the cake and roll up the roulade. Dredge the top with a little icing sugar, cocoa and grated chocolate.