Preheat the oven to 350°F (175°).
Put the ingredients for the pie crust in a bowl and mix together into a firm dough.
Divide the dough into eight small forms, 3 inches (8 cm) in diameter, or one larger spring form.
Prebake for 10 minutes if you're making small pies and 15 minutes for one large pie.
Meanwhile, make the filling.
Put the pumpkin cubes in a pan together with heavy cream and butter.
Bring to a boil, reduce heat, and let simmer on medium low until the pumpkin is soft and most of the cream is absorbed. It will take at least 15–20 minutes. Keep stirring. Set aside and let cool a little.
Add eggs and spices and mix into a smooth puree with a hand blender or in a food processor.
Pour the filling into the pie crust and bake for 15–20 minutes until the filling is firm, a little longer for a large form.
It may be a good idea to lower the heat towards the end and cover the edges with a strip of aluminum foil so that the crust doesn't burn.
Whisk the heavy cream with a hand mixer until soft peaks form and stir in the lemon zest. Serve with the pie.
If you’re limiting your dairy intake, you can replace the heavy cream with a creamy coconut milk. For the crust and filling you can replace butter with coconut oil or ghee. The pie freezes well, which means if you make a couple of extra pies you’ll always have one ready for unexpected company!