Place the pineapple cubes and caster sugar in a large bowl and mix together so that the pineapple is coated with the sugar.
Place a small frying pan over a medium heat and add the pineapple cubes and sugar to the pan. Cook for ten minutes, keeping the pineapple cubes moving as the sugar begins to caramelise evenly.
To make the rice pudding, place all of the ingredients into a medium saucepan and bring the mixture to the boil. Reduce the heat to a simmer and cook for eight minutes, stirring regularly, until the rice has softened.
To serve, place the rice pudding in a bowl and place the caramelised pineapple on top.