Beat the eggs well with the egg white, sugar and pinch of salt. Combine the starch, flour, cocoa and baking powder and sift them, then gradually add them to the egg mixture.
Invert the ready layer onto a moist towel. Remove the baking paper carefully and sprinkle with a liqueur of your choice or rum. Roll it up and leave it to cool completely.
Then unroll it, smear it with the whipped cream that's been beaten with the vanilla and roll it up again. Sprinkle the chocolate roll with cream and powdered sugar.