The crust:
Mix in a food processor, the flour, parmesan, sugar, cornmeal, rosemary, and baking powder.
Incorporate the butter into the mixture by pulsing until a coarse crumb is obtained.
Mix the water and sour cream until homogeneous, then add this mixture to the flour mixture.
Pulse until a dough is formed and refrigerate for 1 hour.

Preheat the oven to 375°F (190°C)

The filling:
Combine the apple butter and sour cream, and set aside.
In a large bowl, mix the apples, sugar, and rosemary.

Roll out the dough on a lightly floured surface to a disk of about 18″ (45cm) in diameter.
Place the dough on a baking sheet (or a pizza sheet).
Spread the apple butter mixture in the center of the dough, creating a circle of about 9″ (23cm) in diameter.
Pour the apples over the apple butter mixture.
Fold the edges of the dough over the apples, making about 6 folds (creating an opening of about 4″ (10cm) in the middle.

Brush the dough with the egg wash and sprinkle lightly with grated parmesan.
Bake for 45 to 50 minutes, until the crust is golden brown.
Let cool for at least 20 minutes before cutting.