In a large bowl, combine the apples, blackberries, sugar, cornstarch, lemon juice, vanilla, and apple pie spice and salt.
1 ½ pounds apples, 24 ounces fresh blackberries, 1 cup granulated sugar, ¼ cup cornstarch, 2 tablespoons freshly squeezed lemon juice, 1 tablespoon apple pie spice, 1 teaspoon pure vanilla extract, ¼ teaspoon salt