Make the pastry – use your fingertips to rub the butter into the flour until it resembles breadcrumbs. Add the sugar then the egg and combine to form a soft dough. If too dry add a little cold water. Wrap in cling film and chill for at least 30 minutes or while you make the filling.
Boil the squash in a large saucepan covered in water for around 15 minutes or until softened. Drain and allow to cool.
Preheat the oven to 180°C/160°C fan/Gas mark 4.
Roll out the pastry on a lightly floured surface and use to line a 22cm loose bottom tart tin. Chill for 10 minutes then line and fill with baking beans or rice. Bake for 15 minutes before removing the beans and lining paper and bake for a further 5 minutes.
Increase the oven temperature to 200°C/180 fan/Gas mark 6.
Use a blender to blitz the squash then push through a sieve so the puree is smooth. Add the sugar, nutmeg and cinnamon to the puree and combine. Beat the eggs, melted butter and milk together then also add to the squash and stir.
Pour the mixture into the tart tin and bake for 10 minutes before reducing back down to 180°C/160°C fan/Gas mark 4. Bake for a further 40-45 minutes until the filling is just set.
Leave to cool before removing the pie from the tin and serving with a dollop of clotted cream and a sprinkle of cinnamon sugar.
