Combine both flours and salt in a medium bowl. Add the butter and shortening, then use a pastry cutter or fork to break down the fat until it becomes the size of peas.

Pour in ¼ cup of water and mix gently with a rubber spatula until the dough just starts to form a shaggy mass. Add more water one tablespoon at a time if needed. Use your hands to press the dough until it just comes together - do not overmix.

Form the dough into a rectangular shape, then wrap in plastic and refrigerate for a minimum of 30 minutes (or up to two days). Dough can be made and frozen up to 6 months in advance.

Add bacon to a large pot and saute over medium heat until crisp, about 8-10 minutes. Use a slotted spoon to transfer bacon to a dish, leaving most of the fat behind. Add onions and turn up the heat to high. Stir, then cover, and let cook until wilted, about 5 minutes. Continue cooking, covered, then stirring every 5 minutes or so, adding a tablespoon water as needed to prevent sticking. When the onions are very soft and starting to darken in color, add the mushrooms and season with salt and pepper.

Continue cooking uncovered, stirring and adding water every so often to deglaze the bottom of the pan if it gets dry. Turn the heat down to medium, then cook until the onions and mushrooms are deep brown and caramelized, about 15 minutes more. Add garlic and sage, then cook for one to two minutes.

Sprinkle flour over, then stir until incorporated. Add stock, turn the heat back up to high, and stir until it thickens. Simmer for 5 minutes, then remove from the heat.

Stir in the reserved bacon, turkey and heavy cream, then gently fold in the butternut squash, being careful not to mash it. Taste and season with more salt and pepper as needed (it will need it). Let mixture cool completely.

Preheat the oven to 375 degrees F. Roll crust out on a piece of parchment paper to a rectangle measuring 11"x16", then transfer to a sheet pan. Cut into 6 equal squares, then use the tip of your knife to score an X in the middle of each square. Cover loosely with plastic wrap, then chill until ready to use.

Divide the turkey mixture into 6 4-oz ramekins, then place them on a sheet pan. Brush the perimeter of each ramekin with egg wash. Place a dough square on top of each ramekin, being sure to center the X as best as possible. Gently press down on the edges to create a seal, but don't press too hard or the dough will break. Brush all over with egg wash, then sprinkle lightly with flaky sea salt and pepper.

Bake for about 30-45 minutes or until the dough is deep golden brown. Allow the pot pies to cool 5-10 minutes before serving.