Combine together butter (soft, room temperature) and sugar and knead until you have a smooth dough. Add one by one the eggs and the yolk and keep kneading. Just in the end add the flour, vanillina and lemon zest. Knead until you have a smooth dough. Wrap it with film and let it rest for 10 minutes in the fridge.
Punch down the dough anf roll it out to a ½ cm thickness. Place the dough in a parchment lined baking pan. Add the jam and finish to decorate with some dough's stripes. Bake at 150°C for 30 minutes and at 160°C for the last 5 minutes.