Caramel Apple Oat Squares

1-3/4 cups all-purpose flour 1 cup quick-cooking oats 1/2 cup firmly packed brown sugar 1/2 tsp. baking soda 1/2 tsp. salt 1 cup cold butter or margarine 1 cup chopped walnuts 20 caramels, unwrapped 1 can (14 oz.) sweetened condensed milk (NOT evaporated milk) 1 can (21 oz.) apple pie filling

Preheat oven to 350°F. In large bowl, combine flour, oats, brown sugar, baking soda, and salt; cut in butter until crumbly. Reserving 1-1/2 cups crumb mixture, press remainder on bottom of 13x9-inch baking pan. Bake 15 minutes. Add nuts to reserved crumb mixture. In heavy saucepan, over low heat, melt caramels with sweetened condensed milk, stirring until smooth. Spoon apple filling over prepared crust; top with caramel mixture then reserved crumb mixture. Bake 20 minutes or until set. Cool. Serve warm with ice cream. Store leftovers covered in refrigerator. Makes 12 servings.