Cut pineapples in half lengthwise, leaving top with leaves attached if you wish to serve it the pineapple shell.
Remove most of the pineapple from the halves, in one piece if possible, using a paring knife and grapefruit knife. Cut the pineapple inside piece in half lengthwise and cut out the core. Cut in half lengthwise again and then cut each piece into 2.
(You should end up with about 8 long slices from each pineapple.) In a small bowl, combine brown sugar with cinnamon and nutmeg.
Toss half this mixture with the pineapple. Peel bananas just before cooking, cut in half crosswise and lengthwise. Toss with remaining sugar.
Barbecue pineapple or broil until browned and partially cooked, about 8 to 10 minutes.
Cook bananas until browned, about 5 minutes.
Serve "sticks" of pineapple and bananas in pineapple shells with a scoop of sorbet. NOTE: If you are not serving it in the shells, buy the pineapple already peeled and cored.
It can be cut into rounds or sticks.