In a food processor combine the flour, salt, sugar and cold cubed butter, pulse to process until the mixture resembles crumbs. Through the chute of a food processor add ice cold water one tablespoon at a time and pulse until the mixture feels a bit heavier. It will not come together just yet.
Remove the mixture from the food processor and empty into a large bowl. Bring the dough together with two hands, don't handle it too much, just enough to form a shaggy ball. Wrap in plastic wrap, then press the dough down with the palm of you hand to form a disk. Chill in a refrigerator for at least one hour.
Take the shortcrust from the refrigerator and let it come to room temperature for at least 20 minutes. It's impossible to roll out a well chilled disk of pie crust and if you try really hard it will just crack. Once it's pliable enough to work with, start rolling it out on floured surface into a circle 12 inch in diameter. Don't worry if it cracks, just pinch it together and continue on. Drape on your rolling pin and transfer the rolled out shortcrust into a 9 inch pie plate. Once again if it cracks or tears, just patch it up.
Once the pie plate is lined with the shortcrust, fold the overhanging edges under to form a thicker rim, then crimp it decoratively. Chill in the fridge for 20 minutes. Preheat the oven to 200C/400F.
Take the shortcrust out of the fridge, prick the crust with a fork all over, then line it with parchment paper and fill with baking beans. Blind bake at 200C/400F for 15 minutes, then remove the baking beans and the paper and bake for 5 minutes longer. It will probably shrink a bit, which is normal. It should look pale and partially baked.
While the crust is baking, mix the corn syrup and the maple syrup with the brown sugar, melted butter, salt and vanilla. Then whisk in the eggs and add the bourbon and the chopped pecans.
Take the pie crust, that's been blind baked, and fill with the pecan filling, then top with the pecan halves in concentric circles. (You can also skip this step if want less nuts in your pie.) Cover the edges with aluminium foil to prevent excessive browning and burning. Bake in the oven preheated to 350F/180C for 35-40 minutes or until the edges of the pie are set and the centre is still slightly jiggly. Cool completely before slicing and serving.