Mix all filling ingredients in a small saucepan. Bring to boil. Reduce heat simmer until thick, about 10-15 minutes. Cool to room temperature.
Measure rum, add coconut, fill with water, according to the package directions on cake mix box.
Follow the instructions for cake mix.
Use cupcake bake cups, or spray cupcake tins with no stick spray. Cover bottom with batter. (2-3 tbsp of cake mix.)
Place 2-3 tablespoons of the pineapple filling on top of batter.
Fill the tins 2/3 full with more batter.
Bake according to the package directions. (usually 18-21 minutes.)
Soften butter to room temperature. Cream butter with electric mixer. Add rum, vanilla and coconut extract. Cream until combined.
Add 2 cups sifted powdered sugar and mix well. Add the 2-1/2 cups of powdered sugar and a scant 1/4 cup coconut milk. Don't add all of the milk until you see if you need it to get it nice and creamy.
Frost cupcakes and top with toasted coconut and a maraschino cherry.
NOTES**General Baking Tips:Always measure dry ingredients with a dry measuring cup. Measure with dry measuring cups or weigh dry ingredients.Always measure liquid ingredients with liquid measuring cupNever break eggs directly into recipe ingredients. Break eggs into a separate bowl, in case you get any shells, so that you can pull them out.Make sure that you know what temperature your oven is set at. Buy an oven thermometer and check oven temperature regularly.Always check baked goods, like cakes or quick breads with cake tester, placed in center. If the tester comes out clean, it’s done.