Place all ingredients in a bowl or on a work surface. Mix with your hands and quickly work into a shortcrust pastry. Cover and let rest in refrigerator for about 2 to 3 hours. Roll out dough on a floured work surface or between two baking mats to 3 mm thickness with a rolling pin. Sweep off excess flour with a flour whisk or brush before cutting. Cut out any shapes you like. Place on prepared baking sheet and bake in preheated oven at 165 to 175 °C for 12 to 15 minutes until light on sight. Let cool. Spread half of the cookies with jam on one side and place the other half on top.