Apricot Filled Cookies
Stir the butter and powdered sugar together until creamy. Mix in the egg yolks, vanilla sugar, salt and lemon zest. Sift in the flour and knead to form a dough. Divide the dough, wrap in plastic wrap and place in the refrigerator for about 1 hour, then remove and roll out the dough about 3 mm (approximately 1/10 inch) thick.
With a circle cookie cutter (about 3 cm, or approximately 1 inch, in diameter) cut out cookies. Cut out numbers or letter from the center of half ofthe cookies. Bake in a preheated oven (200°C, approximately 400°F, center rack) for approximately 12 minutes.
Heat the apricot jam in a small saucepan until liquified, then pour it through a sieve. Spread all of the cookies with jam, then press the cookies with the cut-outs on top of the cookie bases. Sprinkle with powdered sugar just before serving.