Heat oven to 350°F. Grease bottom of 13x9-inch metal baking pan. In large bowl, combine oats, 1-1/2 cups flour, sugar, baking soda and salt. Stir in butter; mix well. Reserve 1 cup oat mixture; press remaining oat mixture onto bottom of baking pan. Bake 12 to 15 minutes or until golden brown. Sprinkle with chips and nuts. Mix caramel topping with remaining flour in small bowl; drizzle over nuts to within 1/4 inch of pan edges. Sprinkle with reserved oat mixture. Continue baking 18 to 22 minutes or until golden brown. Cool in pan on wire rack; refrigerate until firm. Cut into bars.