Preheat your oven to 350°F (175°C) and prepare a jelly roll pan.
Whisk eggs and sugar until pale and fluffy.
Sift in flour and cocoa powder and fold gently.
Pour batter into the prepared pan and spread evenly.
Bake for 12-15 minutes until the cake springs back when touched.
Prepare a clean kitchen towel dusted with powdered sugar.
Turn the cake onto the towel and peel off the parchment.
Roll the cake from the short side with the towel and let cool.
Unroll the cooled cake and spread with filling.
Roll it back up without the towel and dust with powdered sugar.