Place the flour, butter pieces, powdered sugar, egg and salt into a big mixing bowl.
Mix the content and work the ingredients so that they start to incorporate. Then add around 30 milliliter water to the dough and mix it in. If you need little more water, do so and create a smooth dough.
Keep the dough to rest for 1 hour in the fridge.
Take a Tart form and place it on a baking paper. Draw around the form on the paper with a pencil and cut it out. We will need it later!
Butter the Tart form and dust it well with flour. That will prevent the dough to stick on the form while baking.
Preheat your oven to 390° Fahrenheit/ 200° Celsius.
Take out your dough and roll it out to approximately 0.2 inch/ ½ cm thickness. Turn the baking form and place it on the dough. Calculate 2 cm more from the form and cut out all around.
About 0.8 inch/2 cm more are required or your dough will be too short to fit into the baking form.
Place the cut out dough into the buttered form and poke with a fork a few fine wholes into it.
Add the previously cut out baking paper on top with some weight such as a handful of beans or lentils. That will prevent the dough to blow up in the center and to stay even. Bake the dough by itself for 10 mins at 390° Fahrenheit/ 200° Celsius.
Once the dough is finished baked, take it out and remove the baking paper with the beans/lentils. Pour the vanilla sauce into the tart and spread evenly.
Decorate with blueberries and sprinkle the sugar on top.
Bake the tart at 390° Fahrenheit/ 200° Celsius for about 20 minutes or until golden.