Bake the cleaned pumpkin in a moderate oven. Mash it into a puree and fry it in 2 tbsp (30 ml) of oil and a little water, then mix it with 2/5 cup (100 ml) of water and the sugar. Stir the mixture until it thickens. Once cool, add the chopped walnuts.
Knead a dough from the twice-sifted flour, salt, 2/3 cup (150 ml) oil, water, baking powder, then divide it into 2 parts and roll out each one into a thin sheet, the same size as the bottom of the tray.
Put 1 sheet in a greased tray, distribute the filling on top and cover with the second sheet. Press the edges of the 2 sheets together. Bake the Phyllo Pastry Pumpkin Pie for Christmas Eve in a moderate oven.
Once cool, cut it into pieces and sprinkle it with powdered sugar.