Prepare Dough: Make a simple dough by combining flour, sugar, salt, and cold butter until crumbly. Add ice water gradually until the dough forms. Wrap and chill for 30 minutes.
Preheat Oven: Set your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Prepare Filling: Toss thinly sliced apples, fresh or dried cranberries, sugar, cinnamon, and a pinch of salt in a bowl until evenly coated.
Roll Out Dough: On a lightly floured surface, roll out the chilled dough into a rough circle about 12 inches in diameter. Transfer it to the prepared baking sheet.
Arrange Filling: Arrange the apple-cranberry mixture in the center of the dough, leaving a border around the edges. Fold the edges of the dough over the filling, pleating as you go.
Bake and Serve: Brush the edges of the galette with egg wash and sprinkle with coarse sugar for a golden finish. Bake for 35-40 minutes until the crust is golden and the filling is bubbling. Cool slightly before slicing and serving. Enjoy warm or at room temperature.