Knead a dough from the flour, butter, egg, salt and sugar. Press it along the bottom and sides of the form. Put it in the fridge for 1 hour. Mash the boiled pumpkin with the rest of the ingredients for the filling and leave it aside.
Heat the oven to 356°F (180 °C). Put the form with the crust in it and bake no more than 10 min. Then pour the cream into it.
Return to the oven and bake another 15 min. Take the baked cake out and leave it to cool. Then put it in the fridge for 3 hours.
Decorate with cream and serve.