Heat oven to 350°F. Grease 13x9-inch (3-quart) glass baking dish. In large bowl, beat cake mix, water, oil and eggs with electric mixer on low speed about 30 seconds or until blended. Beat on medium speed 2 minutes, scraping bowl occasionally. Pour batter into baking dish. Bake 25 to 35 minutes or until toothpick inserted in center comes out clean.
Meanwhile, in large bowl, mix sauce ingredients. Using long-tined fork, pierce hot cake in baking 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.)
Before serving, in small bowl, beat 1 cup whipping cream until stiff peaks form. Spread over cold cake. Sprinkle with coconut and macadamia nuts. Cover and refrigerate any remaining cake.