Boil or microwave sliced potatoes for 5-7 minutes until fork-tender but still firm, then drain completely and pat dry with paper towels.
4 cups potatoes
Roll chilled pie dough out to ⅛-inch thickness on parchment paper, keeping edges rough and rustic, then transfer parchment to a baking sheet.
1 sheet pie dough
Spread caramelized onions evenly in the center, then layer overlapping potato slices, shredded cheese, and cooked bacon, leaving a 1-2 inch border around the edges.
1 cup yellow onions, 4 cups potatoes, 1 cup Gruyere cheese, 4 bacon
Fold the dough edges over the filling, pleating as needed to create a rustic folded crust that encloses the filling.
1 sheet pie dough
Brush the crust with egg wash. Bake at 375°F (190°C) for 30-35 minutes until edges are golden and crisp. If using, add cracked eggs to the galette center halfway through baking. Remove when done and let rest 5 minutes before slicing.
1 egg
