Preheat oven to 350° and grease a 9x13-inch pan with cooking spray.
Prepare the cake batter according to package directions.
Sprinkle the coconut and macadamia nuts onto the bottom of the prepared pan.
Spread your cake batter over the top. Set aside.
Meanwhile, in a large bowl, combine the cream cheese, butter, confectioners' sugar, vanilla, and salt.
Beat with a mixer until combined. Dollop the mixture over the cake and use a knife to marble.
Sprinkle white chocolate chips on top and bake for about 55-60 minutes, or until the center is set.
Serve warm with ice cream, if desired.