In the bowl of a food processor, combine the flour and kosher salt. Pulse once or twice to mix. Add the diced cold butter and pulse several times until the butter resembles small peas. Pour the ice water into the food processor while pulsing. Continue pulsing until the dough begins to stick together in small clumps.
Dump the dough mixture onto the counter and use your hands to press it together. Divide the dough in half and shape each piece into a flat disc. Cover with plastic wrap and chill for at least 1 hour.
Potato Bacon Pie
In a skillet, cook the chopped bacon until it's brown and crispy. Transfer to a paper-towel lined plate to drain. Spoon off all but 1 tablespoon of the bacon fat from the skillet. Add the diced onions to the skillet and sauté for 4 to 5 minutes on medium heat. Cook the onions until softened and beginning to brown. Transfer the onions to a bowl and add the bacon. Set aside to cool.
Using a mandolin or food processor with a slicing attachment, thinly slice the potatoes. In a measuring cup, combine the heavy cream, flour, kosher salt, and pepper. Whisk together until there are no lumps. Set aside.
Preheat the oven to 350°F. Lightly grease a 9” pie plate. On a lightly floured surface, roll one disc of dough out into a circle. The dough should be around 2 inches wider than the pie plate on all sides. Carefully fold the dough in half then lift it into the pie plate. Unfold the dough and arrange it in the pie plate letting the excess hang over the edges.
Arrange 1/3 of the potato slices in the pie crust. Top with 1/3 of the bacon and onions followed by 1/3 of the cheese. Drizzle 1/3 of the cream mixture over the potatoes. Repeat two more times with the remaining ingredients. Reserve a few slices of potato to place on the top layer of cheese.
Roll out the remaining disc of dough into a circle that is a little wider than the pie plate. Brush the bottom edge of the pie crust with the beaten egg. Place the top crust over the pie and press down to seal the edge. Trim the excess pie dough around the edge and crimp to create an attractive crust. Brush the top of the crust and the crimped edges with the egg wash. Cut several slits in the top crust for steam to escape.
Place the pie on a baking dish to catch any drips - the filling may bubble over while baking. Bake for 60 to 75 minutes, although it may take up to 90 minutes until the crust is brown and the potatoes are fully cooked. Check the pie after 1 hour to see if the potatoes are cooked. Check the potatoes are done by inserting a paring knife through the steam slits. If the pie crust is getting too brown, cover with a piece of foil.
When the potato pie is fully cooked, set it aside to allow it to cool somewhat. It will be hard to cut the pie while the filling is hot straight from the oven. Let the pie sit for about 15 to 30 minutes. Slice and then serve. Enjoy!