To Make Vanilla Sugar: Combine 1 1/2 to 2 cups sugar with a rinsed and dried vanilla bean in a jar. Cover and shake well. Shake occasionally for 2 -3 days. Use flavoured sugar, replenishing with fresh sugar, as needed.
Beat butter until soft and fluffy. Mix in the icing sugar, vanilla sugar and salt until mass has a lighter colour.
Beat the egg white into the creamed mixture, making sure to incorporate fully. Add in the flour and mix. Cover the dough and rest the dough in the refrigerator for one hour.
Take the dough out of the refrigerator and roll it out until it is about 1cm thick. Cut out circles with pastry cutters. Cut smaller shapes into the middle of half of the circles.
Bake in a preheated 200 degrees C oven for 6 to 8 minutes.
Warm up jam. Put some jam on the biscuits without the holes in the middle. Then put the biscuits with the holes on top of the ones with jam. Sprinkle a bit of icing sugar on top to make them look nice.