Whisk the butter, sugar, vanilla sugar, eggs and lemon flavouring with the bamix® whisk until very foamy. Mix the flour well with the baking powder and stir in with the bamix® multi-purpose blade. Pour the mixture into a piping bag. Use the piping bag with the star nozzle. With the piping bag, pipe the dough onto a greased baking tray using any desired shape. Bake in a preheated oven at approx. 160 °C for 10 to 15 minutes. When the spritz biscuits have cooled down, spread apricot jam on the underneath side of one biscuit and sandwich it together with a second biscuit. Coarsely chop the couverture with the bamix® processor, then heat it up in a bain marie and dip one half of each biscuit in it. Place on a paper to dry.