Preheat the oven to 180°C (350°F). Grease and line a Swiss roll pan with baking paper.

In a bowl, sift together the cocoa powder, flour, and baking powder.

In a separate bowl, beat the eggs and sugar until pale and thick. Fold in the dry ingredients gently.

Pour the mixture into the prepared pan, spreading evenly. Bake for 10-15 minutes.

While the cake is baking, whip the cream until it holds firm peaks and melt the chocolate gently.

Once baked, let the cake cool slightly, then spread the whipped cream over it and roll it up into a log.

Spread the melted chocolate over the log and garnish as desired. Let it set before serving.