Heat the oven to 190 C / 375 F. Line the pie shell with parchment paper and fill with pie weights or dried beans.

Bake for 15 minutes until the edges are just set and lightly golden. Remove the weights and parchment, then set the shell aside. Reduce the oven temperature to 175 C / 350 F.

In a medium mixing bowl, combine the sugar and sifted flour. Whisk them together until evenly mixed.

Pour in the heavy cream, vanilla extract, and salt. Whisk firmly until the mixture is completely smooth with no flour streaks or lumps visible.

Set the blind-baked pie shell on a baking sheet. Pour the cream filling into the shell - it will be quite liquid at this stage.

Scatter the cubed butter evenly across the surface of the filling.

Mix the cinnamon and nutmeg together, then dust the spice blend evenly over the top of the filling.

Bake at 175 C / 350 F for 45 to 55 minutes, until the edges are set and puffed and the center has only a slight wobble when you gently shake the pan. The top should be lightly golden with a faint spiced crust.

Remove from the oven and allow to cool on a wire rack for 1 hour at room temperature.

Transfer the cooled pie to the refrigerator and chill for at least 3 hours, or overnight. The filling will firm up completely as it cools.

Slice with a sharp knife and serve cold or at cool room temperature.