Add diced butter, and work in with a pastry blender or two forks until the mixture resembles coarse crumbs. (glutenfreenosh.com)
Put apple mixture in foil pouch (see potatoes directions above), dot with diced butter, seal tightly and grill until apples are tender, about 15 to 20 minutes. (farmflavor.com)
Add diced butter and mix on low until butter is incorporated. (eatpicks.com)