In a food processor (or a bowl) combine flour, salt, and sugar. Pulse (or cut) butter into flour mixture. Continue to pulse a few more times until butter resembles pea-sized chunks. Pulse ice water in, 1 tablespoon at a time, until dough begins to come together. (Test your dough by pinching some together with your fingers. If it holds together, it is ready.)
Remove from food processor (or bowl) onto a piece of plastic wrap. Form into a disc and wrap in plastic. Place in refrigerator to chill for one hour (or up to two days).
Preheat oven to 400 degrees Fahrenheit and line a baking sheet with parchment paper. Set aside.
Peel and dice apples into 1 inch cubes and place into a medium bowl. Add brown sugar, cinnamon, nutmeg, flour, and vanilla extract. Toss to coat.
Remove dough from refrigerator and separate into 6 equal pieces. Roll each piece of dough into a rough circle, about ⅛" thick.
Distribute apple filling between the 6 pie crusts. Fold dough up around apple filling and pinch together, leaving a 'window' open on top.
Whisk together the egg and water. Gently brush egg wash over each galette to coat the crust. Sprinkle sugar over egg wash.
Bake for about 30-35 minutes, or until crust is golden brown. Remove and allow to cool for 5 minutes before transferring off baking sheet. Galettes can be served warm, room temperature, or cold.
Optionally: Serve with whipped cream or vanilla ice cream.
Store-bought pie crust can be used instead if desired. This recipe uses about 1 and ⅓ store bought pie crusts.
Leftover pies will keep for 4 to 5 days in a tightly sealed container in the refrigerator. Fruit pies can be stored at room temperature for up to 2 days, as long as the filling includes sugar (which acts as a preservative).