Mix cake batters according to manufacturer’s instructions. Using a nonstick 8-inch bundt pan that has been treated with pan spray, deposit 12 oz coconut batter, 8 oz chocolate batter, and then 4 oz coconut batter. Using a toothpick or paring knife, swirl batter, being careful not to touch the sides of the pan. Bake at 350°F until the cake springs back lightly when touched. Let cool 10 minutes, depan, and let cool completely. Decorate with chocolate icing and sprinkle with toasted flaked coconut.