Sift the flour with the baking powder. Make a well in the center and add the egg, vanilla sugar, lemon zest and powdered sugar. Knead the cold butter on the table until smooth and add it as well. Now work everything into a dough as quickly as possible. While doing this, work the ingredients into a dough between the heel of your hand and the table. Chill the dough.
Roll out the dough on a floured surface and cut out circles with a cookie cutter and place on a baking tray.
Bake at about 180 degrees for about 15 minutes. Spread jam on one cookie at a time. Place a second cookie on top of the jam coated one. Brush with glaze of your choice or egg white.
Then sprinkle with sugar confetti.
You can also dip the cookies in chocolate and then sprinkle the sugar confetti on the almost dried cookies.