In a mixing bowl, combine the dry cake mix, oats and butter until blended; set aside 3⁄4 cup for topping. Add egg to the remaining crumb mixture and mix well. Press into a greased 12-inch pizza pan. Build up edges and flute if desired. Bake at 350 degrees for 12 minutes.
Spread pie filling over crust to within 1 inch of edges. Combine the nuts, brown sugar, cinnamon and reserved crumb mixture; sprinkle over filling. Bake for 15-20 minutes or until lightly browned. Cool on wire rack. Refrigerate any leftovers.