1. For the crust, pulse the flours, sugar and salt to combine in a food processor (or the dough can be prepared by hand or using a stand mixer fitted with the paddle attachment). Add the butter and pulse it in quick pulses until just small pieces of butter are visible and the mixture as a whole just begins to take on a pale yellow colour (indicating that the butter has been worked in).
2. Stir the egg yolk, water and lemon juice together and add this to the dough all at once, pulsing until the dough barely comes together (it should look like a crumble dough). Shape the dough into a disc by hand, wrap and chill for at least 2 hours before rolling. Alternatively, the dough can be frozen for up to 3 months and thawed in the fridge before rolling.
3. On a lightly floured work surface, roll out the dough to just under a ¼ inch thick. Lightly dust a 9-inch pie plate (do not grease) and line the plate with the pastry, Trim the pastry off right to the edge of the pie plate and press it down gently to secure. Reserve any remaining dough for trim and chill it and the pie shell while preparing the filling.
4. Preheat the oven to 400 F.
5. Whisk the pumpkin purée, brown sugar and eggs together, then whisk in the evaporated milk, ginger, cinnamon, clove and salt. Pour this into the chilled pie shell.
6. To create the trim, roll out the remaining pie dough into a long rectangle and cut into strips about 1/3-inch wide. Braid three strips together, gently pulling the dough a little to stretch it as you braid it. You may have to make a few braids to cover the complete edge of the pie. Lightly brush the edge of the pie dough and place the braided dough overtop, lightly pressing. Brush the braid(s) with eggwash.
7. Place the pie onto a baking tray and bake the pie for 10 minutes at 400 F, then reduce the oven temperature to 375 F and bake the pie for another 35 to 40 minutes, until the pumpkin filling is set, but still has a little jiggle to it in the centre. Cool the pie to room temperature, then chill completely, about 4 hours, before serving.
The pie is best served chilled, and can be stored, refrigerated, for up to 2 days.