Preheat the oven to 350 deg F.

Place the squash (or pumpkin) on a baking tray, carefully pierce once or twice with the tip of a sharp knife, then bake in the oven for 1 hour 30 minutes, or until golden and very soft, then transfer to a board to cool completely.

For the pastry, mix the flour and icing sugar in a large bowl. Finely grate in the orange zest. Chop the butter into cubes, then rub in with your fingertips until the mixture resembles breadcrumbs.
Beat and stir in 1 egg, then gently scrunch the dough into a ball – be careful not to overwork it. Wrap and rest in the freezer or fridge for 30 minutes.

Slice the pastry lengthways into pieces just under 1cm thick, then distribute around the sides and base of a 26cm loose-bottomed tart tin. Use fingertips to press them together really well and create one piece of pastry, letting it bulge above the brow of the tin (don’t worry if it’s not perfect, just try to create a fairly even layer). Place in the freezer to chill while you crack on with the filling.

Once the squash (or pumpkin) is cool enough to handle, remove the stalk and, using a knife and tongs, carefully slice lengthways, down the middle. Scoop out the seeds and put aside for tasty cooking another day, then weigh out 400g-450g of squash flesh.

Whiz the flesh in a food processor until smooth with the remaining egg yolks (reserving the whites for later), sugar, vanilla bean paste, double cream, ground spices, a good few gratings of nutmeg and a pinch of sea salt.

In a clean bowl, whisk the reserved egg whites with a pinch of salt until stiff glossy peaks form. Fold the squash/pumpkin mixture into the egg whites and pour into the pie crust.
Bake at the bottom of the oven for 45 minutes, or until the filling is set and the top slightly cracked. Transfer to a wire rack and leave to cool completely.