2 pie crusts, homemade or store-bought

4 cups of peeled and sliced apples, preferably Granny Smith or Honeycrisp

1/2 cup of granulated sugar, divided

2 tablespoons of cornstarch

1 teaspoon of cinnamon

A pinch of salt

2 cups of fresh or frozen raspberries

1/4 cup of water

1 egg, beaten

Coarse sugar, for sprinkling

Whipped cream or vanilla ice cream, for serving (optional)