Spray a 9-by-13-inch baking dish with nonstick cooking spray.
Prepare the cake mix in a bowl according to the package instructions. Pour into the prepared baking dish and bake according to the instructions. Let cool for 10 minutes.
Combine the heavy cream, sugar and coconut extract in a chilled metal bowl. Whip the cream with a whisk or electric hand mixer until soft peaks form. Refrigerate.
Using the handle of a wooden spoon, poke holes in the cake, 6 across in each of 4 rows, to make 24 holes. Press a cherry into each hole.
In a medium bowl, whisk together the cream of coconut, crushed pineapple and rum. Slowly pour and spread over the cake and let stand until the liquid is absorbed into the holes, about 10 minutes.
Spread the whipped cream over the top of the cake, sprinkle with toasted coconut and garnish with the leftover maraschino cherries.