Preheat oven to 350°.

Arrange pie crust on baking sheet.

Evenly spread apple pie filling into crust; set aside.

Combine flour with brown sugar in medium bowl. Stir in mayonnaise with fork until mixture is of size coarse crumbs.

Stir in walnuts; evenly sprinkle over apples.

Bake 45 minutes or until golden and bubbling.

Cool slightly on wire rack.

Serve warm or at room temperature and, if desired, with ice cream.