Raspberry Almond Thumbprint Cookies
Using a hand mixer, beat the butter, sugar, vanilla sugar, salt and egg yolks together until smooth and creamy. Stir in the flour and ground almonds. Shape the dough into two rolls, about 3 cm (approximately 1 inch) in diameter, cover with plastic wrap and refrigerate for 2 hours.
Preheat the oven to 200°C (approximately 400°F). Line a baking sheet with parchment paper.
Cut the rolls of dough about 2 cm (approximately 3/4 inch) thick and roll the pieces into balls. Flatten the balls onto the prepared baking sheet and make an indentation in the center using your thumb or the back of a spoon. Bake for 12-15 minutes, until golden brown.
While the cookies are still warm, spoon a small amount of raspberry jam into the center depression. Allow to cool completely.
Store in an airtight container.