Aye, I do a spice cake mix from a box usually just sub half the water for the same amount of pineapple juice. I then shave some very expensive (it has to be for me!) semi sweet chocolate off my big block I keep in the deep freeze and mix that gently into the mix (for one box of cake mix I do at least 1 cup of shaved chocolate, not packed though!) Put it in mini bundt cake pans that were buttered, then dusted with powdered sugar, and bake as the box directions said to.
While those are baking I make the simple syrup with rum, I do 2 parts syrup to 1 part rum, and let it simmer until reduced by half. Let it cool on the stove, and then when cakes are cool, submerge into the simple syrup for a min, then set aside on a cooling rack that was placed in a half sheet pan to catch drips, do this to the rest, let them dry for about 10 mins, then repeat that process another 4 or 5 or 6...or more times

Let them rest for at least 24 hours on the drying rack then you can vacuum seal them and freeze for future use, or just dig in
