Heat oven to 400°F. Butter 9-inch glass pie plate.
In 2 1/2-quart microwavable bowl, microwave 1/2 cup butter uncovered on High 30 seconds, adding 10 seconds as needed until butter melts. Stir in flour, oats, nuts and sugar. Press in bottom and side of pie plate. Bake 11 to 13 minutes or until edges are golden brown.
Meanwhile, in 1 1/2-quart bowl, dissolve gelatin in boiling water. Stir in pie filling. Refrigerate until thickened, about 1 hour.
Pour filling mixture into crust. Spoon sour cream by tablespoonfuls on top. Cut through sour cream and lightly fold filling over it, making swirls. Refrigerate 2 hours or until cold. Top individual servings with whipped cream. Cover and refrigerate any remaining pie.