Heat a pot with water over medium heat and bring it to boiling. Add the grated pumpkin to the pot and the half of the butter. Cook it till soften.
In a large bowl or food processor prepare the dough by mixing together all the ingredients and knead until you get a soft dough. Leave it for an hour to double its size.
Split the ready to use dough into 12 pieces.
On a floury surface roll out each piece into a thin sheet.
Use an oily round baking dish and start placing a sheet at the bottom then spread ingredients (pumpkin, sugar, walnuts, and cinnamon) on top then add another sheet and repeat the process.
Roll the sheets in the baking dish and shape them to form circle starting from the middle of the dish and going toward the edge.
Preheat the oven to 390°F.
Pour the remaining butter on top.
Place the baking dish and bake until golden brown or for about 30 minutes.
Serve warm with sprinkled powdered sugar on top.