Drain the pineapple cubes in a strainer. Lay the pineapple cubes on a paper towel and pat dry. Put the butter in a medium saute pan over medium heat. Make brown butter by heating the butter until melted and just starting to brown around the edges. Add the pineapple and toss to coat in the butter. Add the honey and toss to coat the pineapple with the honey. Cook until the pineapple is golden, about 5 to 7 minutes. Turn off the heat and stir in the pine nuts.
In a small bowl mix together the rum and the mascarpone. Place the pineapple mixture in a serving dish and top it with a dollop of the cheese mixture. Serve immediately.