Almond Shortbread Cookies
Combine the pastry flour, ground almonds, salt and powdered sugar in a large bowl. Add the egg yolk and distribute the butter over the top. Mix everything together using a pastry cutter or two forks. Quickly knead with hands to form a smooth dough. Wrap with plastic wrap and refrigerate for about 1 hour.
Preheat the oven to 180°C (approximately 350°F). Line a baking sheet with parchment paper.
Roll the dough out onto a floured surface to about 3 mm (approximately 1/10 inch) thick. Cut into triangles and place on the prepared baking sheet. Whisk the egg yolk with 2 tablespoons of water. Brush the cookies with the beaten egg yolk and sprinkle with the slivered almonds. Bake for 10-15 minutes, until golden brown. Remove from the oven, sprinkle with the sanding sugar and let cool.