Add ingredients, except the vanilla, together in a medium saucepan and place over medium heat bowl and mix together with a spoon. Let it boil for 1 minute and then take a potato masher and mash up the pineapple to break it up and release the juices. Continue cooking until it thickens up.
Remove from heat and add the vanilla and stir together. Set aside to cool slightly.
For the sundaes:
Place coconut in a sauté pan and set over medium heat. Let it heat until it starts to brown and get toasty. Remove from heat and transfer to a small bowl to stop the toasting process.
Spoon a few scoops of ice cream into 6 serving glasses. Top with a couple tablespoons of pineapple sauce and then sprinkle with toasted coconut. Finish with whipped cream and a cherry.