Melt butter in 10-inch ovenproof nonstick skillet on medium-low heat.
Remove from heat.
Add dry gelatin mix, cornstarch and cinnamon; stir 2 min. until gelatin is completely dissolved. Arrange single layer of apples, cut sides down, in skillet. Top with any remaining apples.
Cook on medium-low heat 8 min.; top with pie crust.
Cut several slits in crust with sharp knife.
Place in oven.
Bake 20 min. or until crust is golden brown and apples are tender. Cool 3 min. Using oven mitts, place large serving plate on top of skillet. Carefully turn skillet over onto plate.