Preheat the oven to 180°C (350°F). In a large bowl, using an electric mixer, beat the eggs and sugar for about 10 minutes. Add the vanilla and salt. Sift the flour and potato starch and fold them into the batter, a little at a time. Line the baking sheet with parchment paper. Pour the mixture into the pan and smooth it out. Bake at 180°C (350°F) for 10-12 minutes. Remove from the oven when it is a light honey color. Place another sheet of parchment paper on top and, while the roll is still warm, roll it up and tighten. Let it cool. Remove the roll and remove the parchment paper. Fill with the hazelnut cream, roll it up, and spread the cream over the outside. Now decorate both sides with chopped hazelnuts. Serve and finish by decorating the center strip with letters and powdered sugar. Cover with cling film until ready to enjoy!