Prepare grill or campfire for low heat, using 12-16 charcoal briquettes or large wood chips.
In a large resealable plastic bag, combine biscuit mix and oatmeal. Add butter; squeeze bag until mixture resembles coarse crumbs. Gradually add milk; knead to form a soft dough. Spread into a greased ovenproof Dutch oven. Combine pie filling and apple juice; pour over dough.
Cover Dutch oven. When briquettes or wood chips are covered with white ash, place Dutch oven directly on top of 6-8 of them. Using long-handled tongs, place 6-8 briquettes on pan cover. Cook for 15 minutes or until filling is bubbly.
To check for doneness, use the tongs to carefully lift cover. If necessary, cook 5 minutes longer. Serve with ice cream if desired.