Prep dough: 1. Combine 2 1/2 cups flour, 3/4 teaspoon salt and 1 cup butter in a mixing bowl. 2. Cut butter in with a pastry blender or two forks. (If you have a food processor, fit it with blade attachment and combine flour and salt; pulse to combine. Add butter, pulse until mixture resembles coarse meal, 10 seconds). 3. Add 1/2 cup water and, using your hands, mix dough until water is incorporated. Form into a ball. 4. Pull dough out onto counter and knead it lightly against counter for a few seconds to distribute butter evenly. (If using food processor, turn on machine and add water in a slow stream through feed tube. Pulse until dough holds together without being sticky.) 5. Gather into a ball and wrap with saran wrap and chill in refrigerator for at least an hour or up to 12 hours. Make: 1. Preheat oven to 375. 2. Peel, core and cut apples into wedges. 3. Toss together with lemon juice, brown sugar, sugar, cinnamon, nutmeg, a pinch salt, 2 tablespoons flour and 2 tablespoons butter. 4. Whisk together egg and 1 tablespoon water and set aside. 5. On a floured surface, roll out dough to 1/4-inch thickness. Transfer to a parchment-lined baking sheet. Mound apples in center of dough leaving about a 2-inch border around fruit. 6. Fold edge of dough over apples. Brush crust with egg wash, sprinkle with 2 tablespoons raw sugar. 7. Bake until crust is golden and the bottom is cooked through, about 55-60 minutes.
This galette dough freezes well. To make dough in advance, wrap tightly with plastic wrap and store in the freezer for up to to 1 month. When you want to make your galette or pie simply transfer dough into your refrigerator to thaw for a day and voila, instant galette dough!