Grease 13 x 9 inch baking dish. To make cake: In large bowl, combine all cake ingredients at low speed until moistened; beat 2 minutes at high speed. Turn into greased baking dish. Bake in preheated 350 degrees F oven 25 to 35 minutes, or until toothpick inserted in center comes out clean.
To make sauce: In large bowl, combine all sauce ingredients; blend well. Remove cake from oven; cool 5 minutes. Using long tined fork, pierce hot cake in dish every 1 to 2 inches. Slowly pour sauce mixture over cake. Refrigerate cake at least 3 hours to chill. (Cake will absorb most of sauce mixture.)
To make topping: Before serving, in small bowl, beat 1 cup whipping cream until stiff peaks form. Spread over cold cake. Sprinkle with coconut and macadamia nuts. Store in refrigerator.