Prepare the crust by combining flour, salt, and cold butter in a mixing bowl. Use a pastry cutter or your fingertips to work the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces. Gradually add ice water, one tablespoon at a time, mixing until the dough comes together when pressed. Form into a disk, wrap in plastic wrap, and refrigerate for 15 minutes.
1 cup fresh cranberries, 1 pinch salt, 1 cup all-purpose flour, 1/2 cup cold unsalted butter, 2-4 tablespoons ice water
While the crust chills, peel, core, and thinly slice the apples. Place the slices in a bowl and toss with half of the sugar, cinnamon, and cornstarch. In a saucepan, combine cranberries with remaining sugar, cook over medium heat until they burst and release juices, about 8 minutes, then add the apple slices. Cook until the mixture is thickened and the fruit is tender, about 10 minutes. Let the filling cool slightly.
1 cup fresh cranberries, 2 large apples, 1/2 cup granulated sugar, 1 tablespoon cornstarch, 1 teaspoon ground cinnamon
Preheat the oven to 400°F (200°C). On a lightly floured surface, roll out the chilled dough into a rough 12-inch circle. Transfer to a parchment-lined baking sheet. Spoon the filling into the center, leaving a 2-inch border around the edges. Fold the edges of the dough over the filling in a rustic free-form style, pleating as needed.
Brush the exposed crust with the beaten egg to promote browning. Bake until the crust is golden brown and the filling is bubbling, about 40 minutes. Rotate the baking sheet halfway through to ensure even baking. The filling should be thick and shiny, with bubbling edges.
1 cup fresh cranberries
Remove from the oven and let cool for at least 10 minutes. Serve warm or at room temperature, optionally garnished with a dusting of powdered sugar or a dollop of whipped cream.
