1. In a large bowl combine flour, sugar, and salt, cut in cold butter until pea-sized pieces form.

2. Stir in sourdough discard and 1 tablespoon ice water, adding more water if needed, until dough just comes together.

3. Shape dough into a disc, wrap, and chill in the refrigerator for 30 minutes.

4. In another bowl toss sliced apples with lemon juice, brown sugar, cinnamon, nutmeg, and flour or cornstarch.

5. Preheat oven to 400°F (200°C) and line a baking sheet with parchment paper.

6. On a lightly floured surface roll chilled dough into a 12-inch circle about 1/4 inch thick.

7. Transfer dough to the prepared sheet, leaving parchment underneath, and pile apple filling in the center, leaving a two-inch border.

8. Drizzle 1/4 cup salted caramel over the apples.

9. Fold edges of the dough up and over the filling, pleating as needed to form a rustic edge.

10. Beat egg with milk or water and brush evenly over the crust.

11. Bake 35–40 minutes until crust is deep golden and filling bubbles.

12. Let cool on the baking sheet for 10 minutes before slicing.

13. Serve warm with extra salted caramel, ice cream, or whipped cream.

14. Store leftovers in an airtight container at room temperature for one day or refrigerate up to three days; reheat at 325°F for 10 minutes to crisp.