1. Prepare the Dough:

• In a large mixing bowl, combine the all-purpose flour, cake and pastry flour, and salt.
• Cut in the butter or margarine until the mixture resembles coarse crumbs.
• Add the sour cream, egg, and vanilla sugar. Knead the mixture until it forms a soft dough.
• Roll the dough into a plastic wrap and refrigerate. For best results, let it rest in the fridge for several hours or preferably overnight.

2. Make the Poppyseed Filling:

• In a saucepan over medium heat, combine the milk, caster sugar, and vanilla sugar. Heat until the sugar is dissolved.
• Stir in the grounded poppy-seed and semolina.
• Cook the mixture, stirring continuously, until it thickens to a creamy consistency.
• Remove from heat and allow it to cool.

3. Assemble the Cookies:

• Preheat your oven to 350°F (175°C).
• On a lightly floured surface, roll out the chilled dough to about a 1/4-inch thickness.
• Cut out desired shapes using a cookie cutter or knife.
• Place a small spoonful of the poppyseed filling in the center of each cut-out.
• Fold the dough over the filling to create a half-moon shape. Pinch the edges to seal.
• Place the assembled cookies on a parchment-lined baking sheet.

4. Bake and Serve:

• Bake in the preheated oven for 15-20 minutes or until lightly golden.
• Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.