Grate the pumpkin on the large grater or process it roughly in the food processor. If you use Hokkaido pumpkin, you don't have to peel it. If you use another kind of aromatic sweet pumpkin, do peel it first.
Place the grated pumpkin in a medium saucepan, add the water, cover and let cook for about 10 minutes or until soft. Let cool.
Preheat the oven to 200 degrees Celsius/ 390 degrees Fahrenheit. Add the sugar, vanilla extract, cinnamon, and 50 g/ 1/3 cup breadcrumbs to the cooked pumpkin and mix well.
Pour the oil into a small cup. Brush a small square cake pan 20x20 cm/ 8x8 inches with some of the oil.
Cut each dough sheet into four pieces that are as large as the pan you use (See the note for more on this).
Brush the first piece with a bit of the oil. Place it in the prepared pan and place the second one on top. Brush again and repeat with another two pastry pieces.
Sprinkle the remaining tablespoon of breadcrumbs evenly on top of the last pastry sheet. Add the pumpkin mixture and level.
Brush the second batch of dough with the remaining oil and place one on top of the other to cover the pie. Brush the last layer of the dough as well.
Bake the pie for about 25 to 30 minutes or until golden brown and rather crispy on top.
Dust the pie with icing sugar before serving.