Slice your pineapples into 8 one inch thick rounds. Skin the sides and core the middles.
Place the pineapple rings in a shallow tray and pour over the rum. Allow to soak for 2 hours (minimum) in the fridge.
Take your soaked pineapple rings and drain off the excess rum. Place one down then slice a piece of your ice cream (ensuring it is roughly the same size as the pineapple) and place on top of the pineapple. Top with the other pineapple slice, forming a sandwich. Repeat until you have 4 sandwiches.
Dip the ice cream sandwiches in the melted white chocolate then decorate with your desired toppings. Freeze for 10 minutes before eating, to make sure everything is set in place.