Preheat the oven to 190° Celsius

Place the egg whites into a stand mixer bowl

Whisk on high speed until soft peaks form

Add the sugar a tablespoon at a time until completely dissolved

When thick and glossy stop whisking

Lightly beat the egg yolks and gently fold into the mixture

Gently fold in the cocoa powder

When fully incorporated pour the mixture into a lined Swiss roll tray and level off

Bake for 12 minutes

Remove from the oven

Turn out onto a wire rack and carefully peel off the baking paper