Heat the zucchini and lemon juice in a saucepan over medium heat until tender (about 15 min). Mix together sugar, cinnamon & nutmeg and add to the zucchini after about 10 minutes. Let it continue cooking the remaining 5 minutes. Set aside.
To prepare the crust: add cake mix, oats, nuts together and pour the melted margarine over them and mix well.
Spread half the cake mixture evenly into a greased 9X13 pan.
Pour the zucchini mixture evenly over the crust. Distribute the remaining cake mixture over the filling as evenly as possible and bake in a 375 degree oven for 35 min. or until golden brown.
Very good warm plain or with vanilla ice cream, or cold the next day.