Prick sweet potatoes with a fork; place on a microwave-safe plate. Microwave on high for 4-5 minutes or until tender. Cool slightly. Drain pineapple, reserving 2 tablespoons juice; set aside.
Cut a thin slice off the top of each potato and discard. Scoop out the pulp, leaving a thin shell. In a bowl, mash the pulp with butter. Stir in brown sugar and reserved pineapple juice. Fold in ham and half of the pineapple. Spoon into potato shells. Top with remaining pineapple.
Place on a baking sheet. Broil 4-6 in. from the heat for 3-5 minutes or until browned and heated through.