In a food processor, pulse together the all-purpose flour, granulated sugar, and a pinch of salt until combined. Add the cold, cubed unsalted butter and pulse until the mixture resembles coarse crumbs. Gradually blend in applesauce and milk until the dough forms a ball. Wrap in plastic wrap and chill in the refrigerator for at least 30 minutes.

While the crust chills, slice fresh peaches and place them in a mixing bowl. Toss the sliced peaches with granulated sugar, ground cinnamon, and flour. Set aside for 10 minutes.

Preheat your oven to 375°F (190°C). Roll out the chilled dough into a rough circle, about 12 inches in diameter, and transfer it to a baking sheet lined with parchment. Spoon the peach filling into the center, leaving a two-inch border around the edges. Fold the dough edges over the peaches.

Brush the exposed edges of the dough with milk and sprinkle coarse sugar over the crust. Bake for 40-45 minutes, or until the crust is golden brown and the peach juices are bubbling.

Once baked, let the crostata cool on the baking sheet for at least 15 minutes. Cut into wedges and serve warm, optionally with vanilla ice cream or whipped cream.