Preheat the oven to 180ºC.
Separate the yolks and whites of the eggs.
Add salt and granulated sugar to the egg whites and mix with an electric whisk until they are fluffy and white, and soft peaks form.
In a separate bowl, mix the egg yolks with the confectioner’s sugar until creamy.
Add the egg yolks to the whites, add vanilla extract and combine carefully - avoid deflating the mixture as much as possible.
Add the flour and baking powder and mix with a wooden spoon slowly, again trying not to deflate the mixture.
Line a baking tray with baking paper and spread the mixture.
Bake for 12 minutes.
Remove from the oven and transfer immediately to a working surface. Cover it with a kitchen cloth and roll it in - this will help you create the shape afterwards.
Once it gets cold, unroll it and dust it with confectioner’s sugar. Add the jam and spread it evenly.
Roll it back into a log and top with more confectioner’s sugar.