Preheat oven to 400°. Roll the one dough ball out on a lightly floured surface into a 10" x 14" rectangle, then fit into a 9" x13" rectangle pan. Add the apple mixture and sprinkle the butter on top. Roll the remaining dough ball out on the lightly floured surface into a 14" rectangle and cut into 1-inch strips. Arrange 6 dough strips in 1 direction across top of pie, spacing apart. Working with 1 strip at a time, arrange 6 more strips in opposite direction atop first, lifting strips and weaving over and under, forming lattice. Gently press ends of strips to edge of baked bottom crust to adhere. Trim overhang. Bake pie for 20 minutes, reduce oven temperature to 350°, and continue baking until pastry is golden brown, 35–40 minutes more. Set pie aside to cool completely.