Peel, deseed and cube the pumpkin into 1-2cm cubes. Cook the pumpkin in the water in a medium saucepan over a medium heat for about 20 minutes, or until soft. Let it cool slightly while you make the crust (see below). When the crust is ready, add the remaining filling ingredients to the pumpkin and water, and purée or mix well. Pour the filling into the crust and bake at 180C for around 40 minutes. Chill the pie overnight before serving, so the filling solidifies.