Caramel Apple Bars

1 3/4 C all-purpose flour
1 C rolled oats
1/2 C packed light brown sugar
1/2 tsp baking soda
1/2 tsp salt
1 C butter or margarine, chilled
1 (21oz) can apple pie filling
20 caramels
1 (14oz) can sweetened condensed milk
1 C chopped walnuts

Preheat oven to 375. Combine flour, oats and brown sugar in bowl; mix well. Stir in making soda and salt. Cut in butter until crumbly. Reserve 1 1/2 cups oat mixture. Press remaining oat mixture over bottom of 9x13" baking dish. Bake 15 minutes; cool slightly. Spread pie filling over baked crust. Combine caramels and condensed milk in medium saucepan. Cook, stirring continually, over low heat until smooth, about 5 minutes. Pour over pie filling. Mix reserved oat mixture and walnuts in a bowl. Sprinkle over caramel layer. Bake until set, about 20 minutes; cool. Cut into bars.