Prepare Pie Crust: In a food processor, pulse together flour and salt until combined. Add butter in chunks, pulsing until coarse crumbs form. Gradually incorporate ice water until dough forms a ball. Wrap in plastic and chill for 1 hour.

Cook Filling: In a skillet over medium heat, fry bacon until crispy (8-10 minutes). Remove and cool on paper towels. In bacon fat, sauté onions for 5 minutes until softened. Crumble bacon and mix with onions, then set aside.

Slice Potatoes: Peel and thinly slice potatoes to about 1/8 inch thick. Whisk together cream, flour, salt, and pepper in a measuring cup. Set aside with sliced potatoes and bacon-onion mixture for assembly.

Assemble Pie: Preheat oven to 350°F (175°C). Roll out chilled dough to fit pie plate. Layer one-third of sliced potatoes at the bottom, half of bacon-onion mixture, some cheese, and drizzle with cream mixture. Repeat layering two more times.

Add Top Crust: Roll out second dough disc and lay over pie. Seal edges and cut slits in the top to allow steam to escape. Brush with beaten egg to achieve a golden color.

Bake: Place pie on baking sheet and bake for 60-90 minutes. Look for a golden crust and check potatoes for tenderness. Let cool for 15-30 minutes before slicing.