German Chocolate Upside Down Cake

1 cup flaked coconut
1 cup chopped pecans
1 pkg. German chocolate cake mix
1 1/4 cup water
1/3 cup oil
3 eggs
3 1/2 cups powdered sugar
3/4 cup melted butter
8 oz. pkg. cream cheese
1 8 oz. container cool whip (optional)

Heat oven to 375*.  Grease a 9x13" cake pan.  Sprinkle coconut and nuts over bottom of pan.  In large bowl, combine cake mix, water, oil and eggs at low speed with electric mixer until moistened.  Beat on high 2 more minutes.  Spoon batter evenly over coconut and nut mixture.  In another large bowl combine sifted powdered sugar, melted margarine and cream cheese.  Beat until smooth and creamy.  Spoon evenly over batter to within one inch of edge.  Bake at 375* for 43 to 53 minutes or test with a toothpick.  Let cool and top with cool whip, if desired.