In a food processor combine the flour, sugar, salt, and cinnamon. Pulse to mix.
Add the butter and blend until the butter and flour make a loose sandy-like consistency. In a large bowl with a rubber spatula add the dough mixture and 4 tablespoons of water. Use the spatula to incorporate. Keep adding a tablespoon of water at a time until the dough just barely holds together.
form into the shape of a disk and wrap in cling film. Refrigerate for an hour.
Making the sweet potato filling
Skin and cut the potatoes into 4 large pieces. Then with the cut side down slice each part into 4 wedges. Place these in a large pot and cover with cold water. Bring to a boil and reduce to medium and cook for 15 minutes or until the a knife pierces the potatoes easily.
Drain and add to a food processor. Puree until the potatoes are smooth.
In a stand mixer with paddle attachment add 4½ cups of the sweet potato puree.
On medium high speed add the sugar, brown sugar, cinnamon, nutmeg, salt, bourbon, ginger and vanilla. Beat until smooth.
Add the eggs and then the cream.
Pie assembly and baking
Preheat the oven to 325°F or gas mark 3.
Roll out the cinnamon pie dough to line the pie pan. Make sure that the dough has not been stretched when placing it in the pan. Cut the excess dough off and create your edge design.
Pour in the sweet potato filling. There may be extra filling. Do not overfill the pie pan.
Bake for 90 minutes or until the center of the pie has set. Check this by giving the side of the pan a tap. If there is a slight wobble then the pie is ready.
Allow to cool in the oven with the door cracked for an hour, then allow to come to room temperature on the counter before placing in the refrigerator. Allow to cool for at least 3 hours.