Bring a large pot of salted water to a boil. Add the corn and cook until just tender, about 3 minutes. Remove the corn from the water and set aside to cool, 15 to 30 minutes.
Add the cream top of the coconut milk to a small saucepan. Bring to a low boil then reduce to a simmer. Cook over medium heat, stirring frequently, until reduced by half, about 10 minutes.
Meanwhile, grate the coconut with a box grater. When the corn is cool enough to handle, remove the kernels and add to a large bowl. Sprinkle with sugar and half of the reduced coconut cream. Add the grated coconut. Stir to combine. Serve in a banana leaf boat.