Toss ingredients together except butter. Divide mixture among four pieces of 12x15 inch parchment paper. Dot each portion with about 1/2 Tbsp unsalted butter.
Fold the two long ends of the paper over the top of the apple mixture; fold down the ends. Twist the other two ends in opposite directions to close the packet.
Grill the packets over direct medium heat for about 10 minutes. Serve warm with ice cream.