Defrost the puff pastry.
Peel the pumpkin, remove the seeds and cut the flesh thickly. Peel shallots and cut into small cubes. Peel ginger root and grate finely.
Heat butter in a frying pan, add shallots and pumpkin, stir in sugar and sauté for about 8 minutes until soft.
Add ginger and juice of one lemon and season with salt and cayenne pepper. Cool the pumpkin filling.
Preheat oven to 220 °C, roll out thawed puff pastry on a floured surface to a rectangle. Mix egg and brush the edges of the dough with it. Spread pumpkin filling evenly lengthwise on center of dough.
Fold dough over filling. Close ends tightly. Place the pumpkin strudel on a baking sheet with the seam facing down, brush with the remaining egg, prick a few times with a fork and finally top with pumpkin seeds.
Bake the pumpkin strudel in the oven for 20 minutes.