Preheat the oven to 350 degrees F. Spray one 6-inch cake pan and two 1-quart ovenproof bowls with cooking spray. Beat the cake mix, eggs, buttermilk and vegetable oil with a mixer.
Divide the batter evenly among the pan and bowls; bake until a toothpick comes out clean, about 25 minutes for the pan and 35 minutes for the bowls. Cool; unmold.
Trim all 3 cakes to make them level. Hollow out the smaller end of one of the bowl cakes, carving about 1 inch deep. (Leave a thick rim around the edge.)
Put the uncut bowl cake, wider side up, on a cake board or plate. Spread with a layer of chocolate frosting, then position the round cake on top.
Spread the round cake with frosting, then put the other bowl cake on top, carved part up. Freeze the cake about 1 hour (this will make it easier to frost).
Frost the outer rim and inside of the hole with vanilla frosting (an offset spatula works best). Put the remaining vanilla frosting in a resealable plastic bag.
Spread the remaining chocolate frosting over the outside of the cake. Press handfuls of
toasted coconut into the frosting, covering the cake completely.
Microwave the bag of vanilla frosting for 5 seconds (the bag will not melt). Snip off a corner and squeeze the frosting into the top of the cake so it looks like liquid.
Thread dried fruit onto a wooden skewer and insert it into the cake. Add a cocktail umbrella and straw.
Photograph by Kang Kim
Recipe courtesy Food Network Magazine