Topping/Crust:
Melt the butter, add 1/4 spice cake mix, flour*, sugar and walnuts. It will become a crumbly consistency. Take about 1/2 of the mixture and layer the bottom of a greased 9"x13" pan. Press down with hands to make it packed. Bake at 350 degrees for about 15 minutes until golden brown.
Filling:
Mix together pumpkin, egg whites, apple sauce, evaporated milk, pumpkin pie spice and all but 1/4 of the spice cake mix (the remainder is for the crust/topping). Mix well for two minutes, then pour on top of the baked crust.
Topping:
Sprinkle the reserved crumb mixture over the top of the cake batter in the pan.
Bake:
Bake at 350 degrees for approximately 60 minutes (I did about 50 minutes because it stays more moist). Cool and cut into squares.