Camp Oven Surprise Cake

1 box cake mix
1 stick of butter
2 cups water
2 containers pie filling
Line Dutch oven with foil. Empty in pie filling; top with cake mix and spread evenly. Add 2 cups water and butter. DO NOT MIX.
Put lid on and place oven on coals with 10 on lid.
"Bake" about 1 hour.