On a lightly floured surface, roll out the dough to 14-inch round, about 1/8 inch thick.

Transfer dough to a large parchment-lined backing sheet.

Refrigerate until ready to use (up to an hour)

Preheat oven to 375.

In a large bowl, gently toss the peaches, blackberries, sugar, lemon juice, cinnamon, cornstarch and salt.

Arrange everything on top of the dough.

Fold up pieces of the dough so each pieces overlaps.

Brush edges of dough with the beaten egg and sprinkle with sanding sugar.

Bake for one hour or until bubbling, browning and juicy.

Serve warm or at room temp.

In the bowl of a food processor, mix together the flour, cornmeal, salt, and sugar.

Add the butter and pulse until the mixture is like coarse meal.

With the machine running, slowly add the ice water until the dough just comes together.

Turn out onto a floured surface.

Divide in half, place in saran wrap and refrigerate at least one hour or up to 1 day before using.