Place bananas in center of large sheet of heavy duty aluminum foil. Mix melted butter, brown sugar, pumpkin pie spice and vanilla until well blended. Spoon over bananas. Bring up foil sides, double fold top and ends to tightly seal packet.
Grill over medium heat 5 minutes or until bananas are softened, turning packet over halfway through cook time.
Serve with vanilla ice cream, spooning sauce from packet over bananas.