Grease a 12-inch springform pan and line bottom with waxed paper. In a small bowl, dissolve gelatin in water and let it cool. Beat together cream cheese and confectioners' sugar until light and fluffy. Add gelatin and beat until thoroughly mixed. Fold in heavy whipped cream and turn mixture into prepared pan and chill. Blend together graham cracker crumbs, sugar and butter. Sprinkle mixture over chilled cheese cake. Press crumbs into surface lightly. Turn cheesecake over, crumb-side down and remove from pan. Top with chopped apples and walnuts. Generously pour caramel sauce over the top.