Step 1 Preheat oven to 350 degrees F (175 degrees C). Grease and flour two 9 inch pans. Combine the graham cracker crumbs, brown sugar, walnuts and butter. Divide mixture evenly between the prepared pans. Set aside.
Step 2 In a medium bowl, mix together the cake mix, water, orange juice and oil until blended. Beat in the eggs, one at a time, then stir in the orange zest. Pour the mixture evenly over the crunch layer in the pans.
Step 3 Bake in the preheated oven for 30 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool for 10 minutes, then invert onto a wire rack and cool completely before frosting. Frost (crunch side up) between layers, on top and sides. Arrange orange sections on top, then refrigerate.
Step 4 To make the frosting: In a medium bowl, beat the vanilla frosting until light and fluffy, then mix in the whipped topping. Stir in the orange and lemon zest. Use frosting on completely cooled cake layers.