Sift the flour in a large bowl, then cut the butter into cubes and mash them together with your fingers to get crumbs. Add the vanilla and sugar.
Make a well in the middle of this floury mixture and put the beaten egg in it. Knead with a spatula and pour in the water.
Take the dough with your hands and put it on a wooden board, then knead it quickly and form it into a ball. Put it for 30 min. in the fridge to harden.
Take the hardened dough out of the fridge and cut off 1/4 of it. Roll out the bigger part into a circle, larger than the diameter of the pie form, then put it in the form.
Remove the excess dough that sticks out of the form. Pour in the pumpkin filling and distribute it evenly.
From the smaller part, make the pie decoration. Cut off curly strips using a pie roller cutter. Place them on the pie and press.
Bake the pie in a preheated 356°F (180 °C) oven for about 45 min., then sprinkle it with powdered sugar.