Preheat your grill to about 450 degrees.
Spread chopped peach on a 12" x 12" square of aluminum foil.
Sprinkle with brown sugar, oats, and nuts.
Evenly disperse chopped butter over the top.
Fold corners of the foil up towards the center, and crimp the edges together to make it sealed all around.
Cook on the grill for about 15 minutes, or until peaches are cooked to your liking.