1) Preheat the oven to 180°C/gas mark 4.
2) For the pastry. In a food processor mix together the flour and sugar then add the butter, and whiz until the mixture resembles breadcrumbs. Empty into a bowl then beat together the egg and slowly add, mixing until the pastry forms a ball. Wrap tightly in cling film and refrigerate for two hours.
3) Turn the oven down to 170°C/gas mark 3.
4) Roll out the pastry on a lightly floured surface to a 2mm thickness. Use to line a 28cm tart ring placed on a baking sheet. Rest the lined tart ring in the fridge for 20 minutes.
5) Line the tart ring with greaseproof paper and fill with baking beans to keep the base's shape, and bake blind for about 20 minutes. Remove the greaseproof paper and baking beans and return to the oven for 5-8 minutes or until the pastry starts to turn golden brown. Remove from the oven and brush with egg yolk and allow to cool.
6) Turn the oven down to 160°C/gas mark 1.
7) For the filling. Bring the cream, sugar and spices to the boil then quickly whisk onto beaten eggs. Add the pumpkin mix and gently beat in until everything is mixed.
8) Fill the pastry case with the pumpkin mix. Carefully place in the middle of the oven and bake for 40-45 minutes or until the mix appears set but not too firm. Remove from the oven and cover the surface liberally with grated nutmeg.
9) Allow to cool to room temperature before serving.