Work the flour, sugar, vanilla sugar, butter, egg and salt into a shortcrust pastry. Shape the dough into a ball and let it rest in the refrigerator for about 30 minutes, covered.
Almond-cream:
Beat the butter and sugar until frothy and gradually add the eggs and almonds. Mix the mixture into a cream. Stir in the lemon juice.
Grease a tart pan and roll out the shortcrust pastry thinly and press in with a small edge. Spread the almond cream on the dough base. Lightly press the blueberries into the cream.
Bake the tart in a preheated oven at 180 ° C top / bottom heat or 160 ° C fan for about 30 minutes.
After cooling, sprinkle the tart with powdered sugar.