Remove seeds and pulp from the pumpkin. Peel the skin and cut into bite-sized pieces. Place pumpkin and 1 tbsp water in a microwave-safe bowl, cover loosely with plastic wrap, and microwave at 600W for 5 minutes until soft. Drain water.

In a food processor, blend the pumpkin with sugar, cream, beaten egg, and cinnamon until smooth. Let the filling cool.

Dust a cutting board with flour. Roll out one puff pastry sheet larger than the pie pan. Place it in the pan and trim excess pastry, attaching it to the base.

Fill the pastry with the pumpkin filling, smoothing it out and slightly mounding the center.

Cut the remaining pastry sheet into 16 strips. Use 12 strips to create a lattice pattern over the filling. Place the remaining 4 strips around the edge of the pie and press with a fork to seal. Brush the surface with beaten egg.