Spoon pie filling into a 9x13x2 glass baking pan. Grate the lemon zest over the apples, squeeze the lemon juice over the apples. Sprinkle with 1/2 tsp of the cinnamon. Pour the dry cake mix over the apples, spread to the edges of the pan. Sprinkle with the remaining 1/2 tsp cinnamon and the walnuts, drizzle with the melted butter.
Bake 325 for 55-60 minutes or until golden brown and bubbly.