1. Preheat the oven to 375°F.
2. Place butter, flour and powdered sugar in the bowl fitted with the kneading/ crushing blade. Mix at speed 8 for 1 minute or until mixture resembles breadcrumbs. Add egg yolk and 2 Tbsp. water through the opening on the lid. Scrape down the sides of the bowl and mix at speed 8 for 1 minute or until mixture comes together. If necessary, add another 1 Tbsp. water.
3. On a lightly floured surface, knead pastry until smooth. Wrap in plastic wrap and refrigerate for 30 minutes.
4. On a lightly floured surface, roll out half of dough until 1⁄8-inch thick. Using a 3-inch round cutter, make 12 circles. Place in a tart pan and form to sides. Roll out second half of dough. Use a 2 1/2-inch star cutter to make 12 stars.
5. Place teaspoons of mince meat filling into tarts. Top each tart with a star cutout. Press lightly to seal. Sprinkle with sugar. Bake tarts for 22-25 minutes or until lightly browned. Cool for 5 minutes; remove from the pan and continue cooling on a wire rack.