Preheat the oven to 200°C/Fan 180°C/Gas 6. Lightly butter a 23cm tart tin. Line a baking tray with baking parchment or foil.
Cut the pumpkin in half horizontally and remove the seeds. Place the pumpkin halves, cut-side down, on the lined baking tray and bake for
30–40 minutes, or until tender. Remove and leave to cool.
Meanwhile, make the pastry. Sift the flour and salt into a mixing bowl. Rub in the butter until the mixture resembles breadcrumbs.
Stir in 3–4 tablespoons cold water with a palette knife until the mixture forms a dough. Mould it into a ball, wrap it in cling film
(plastic wrap) and chill in the fridge for at least 30 minutes.
Roll out the pastry on a lightly floured surface and use it to line the tart tin, pressing it into the sides. Level the top. Place a sheet of baking parchment inside and fill with baking beans. Bake ‘blind’ for 15 minutes, then remove the parchment and beans. Return the crust to
the oven for 5 minutes, or until the base is golden brown. Remove from the oven and reduce the temperature to 180°C/Fan 160°C/Gas 4.
Scoop the roasted pumpkin out of the skin – you want around 300g. Place in a food processor and blitz until smooth.
In a large bowl, beat the sugar, eggs and egg yolk. Stir in the spices and lemon zest. Add the pumpkin purée and stir in the evaporated milk.
Pour into the pastry case and bake for 45 minutes, or until the filling sets. Don’t worry if it’s still a little wobbly – it will firm up as it cools. Leave to cool in the tin on a wire rack for 1–2 hours.
Cut the pie into slices and serve with whipped cream and a dusting of cinnamon. It will keep well in the fridge for 24 hours.