Preheat the oven to 350 ℉/ 180℃.
To make the filling
In a large frying pan or large pot heat olive oil over medium heat. Sauté onion, green onions and leeks for about 3 minutes. Add pumpkin and sauté until the water from the pumpkin has evaporated. Remove from heat transfer to a big bowl and set aside to cool for few minutes. Season with salt and pepper. Add all the remaining filling ingredients and mix well.
To make the pie
Lay out one sheet of the puff pastry on a large baking sheet lined with a parchment paper. Spread the pumpkin mixture over top, keeping it away from a 2-3cm (3/4-1″) border around the edge.
Lay the second sheet of puff pastry over top of pumpkin filling, and squeeze the border edge together to seal tightly, being careful not to leave any open edges where filling could escape.
Brush the top of the puff pastry with the beaten egg and then cut a few slits in the top of the pastry.
Bake the pie for 30 to 45 minutes, until puffed and golden brown. Let it cool for 15 minutes before serving.
