Cut the butter into pieces. Knead flour, icing sugar, butter and egg first with the dough hooks of the hand mixer, then with your hands to a smooth dough. Wrap the dough in foil and chill for about 30 minutes
Sort blueberries. Bring 75 g blueberries, 1 teaspoon sugar and apple juice to the boil and simmer for about 3 minutes. Puree the blueberries and let them cool down
Roll out the dough 2-3 mm thin on a floured work surface. Cut out 4 circles (each approx. 14 cm Ø). Knead the dough again and roll out again and cut out another 2 circles. Grease the tartlet cups (each approx. 12 cm Ø) and line them with the grease. Cut off any protruding edges. Chill the Tartelettes for approx. 30 minutes
Prick the Tartelett bottoms several times with a fork. Bake in the preheated oven on the lower shelf (electric oven: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 8-10 minutes. Let the tartlets cool down a little, then remove them from the moulds and let them cool down on a cake rack
Cut the vanilla pod lengthwise and scrape out the vanilla pulp with the back of a knife. Add 125 g blueberries to the puree. Whip cream, vanilla pulp and 1-2 teaspoons of sugar until stiff, while letting the cream setting agent trickle in. Pour the cream into a piping bag with a medium perforated spout and squirt in small tuffs onto the tartelettes. Spread blueberries on top and decorate with violet blossoms
waiting time approx. 1 1/4 hours