Apple Galette

In a large bowl, whisk together the 1 1/2 cups of flour and salt. Add the cold, cubed butter and use a pastry cutter or your fingers to work it into the flour until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.
Drizzle the ice water over the flour mixture and stir with a fork until the dough just begins to clump together. Gently knead the dough in the bowl a few times until it forms a cohesive ball. Flatten the ball into a 1-inch thick disc, wrap it tightly in plastic wrap, and refrigerate for at least 30 minutes.
Preheat your oven to 400°F (200°C). On a lightly floured surface, roll the chilled dough out into a rough 12-inch circle, about 1/8-inch thick. Carefully transfer the dough to a parchment paper-lined baking sheet.
In a medium bowl, toss the thinly sliced apples with the 2 tablespoons of sugar, cinnamon, and 1 tablespoon of flour until evenly coated. Arrange the apple slices in a concentric circle on the dough, leaving a 2-inch border around the edges. Dot the apples with the small pieces of butter.
Carefully fold the edges of the dough up and over the apples, pleating as you go. Brush the exposed dough crust with the beaten egg wash and sprinkle the entire galette generously with additional sugar.
Bake for 35-45 minutes, or until the crust is a deep golden brown and the apple filling is bubbling. Allow the galette to cool on the baking sheet for at least 15 minutes before slicing and serving.