Preheat your oven to 350°F (175°C) and grease a 15x10-inch jelly roll pan.
In a large mixing bowl, beat the eggs and granulated sugar until thick and pale.
Sift together flour, cocoa powder, and salt; gently fold into the egg mixture.
Pour the batter into the prepared pan and spread evenly.
Bake for 12-15 minutes, until the cake springs back when touched.
While baking, prepare a clean kitchen towel and dust with powdered sugar.
Once baked, immediately invert the cake onto the towel, removing the pan.
Carefully roll the cake with the towel and let it cool completely.
In a separate bowl, whip the heavy cream, powdered sugar, and vanilla until soft peaks form.
Unroll the cooled cake, spread with whipped cream, and reroll. Chill for 30 minutes before decorating.