place rack in center of oven, bake at 350 degrees. Use a 13X9 cake pan.
Place cake mix, water, oil, and eggs in an electric mixer, mix on low speed 1 minute, scraping down the sides. Beat batter 2 minutes on medium speed. Spread into greased 13X9 cake pan. bake 27 to 29 minutes.
For the FrostingChill bowl and whisk of an electric mixer, pour heavy whipping cream into bowl. Beat until on high speed until cream has thickened. approximately 1 1/2 minutes. Add sugar and beat an additional 1 to 2 minutes.
While cake is still warm, pour over coconut milk spreading across the cake - once cake is cooled apply Whipped Cream frosting and top with a generous amount of sweetened coconut. Chill at least 1 hour.