In medium mixing bowl, combine flour, sugar and salt. Using pastry blender, cut in 1/2 C. butter until mixture resembles coarse crumbs. Press mixture evenly into ungreased 11 x 7 inch pan to form a base. Bake for 15 to 18 minutes until edges are light brown.
In a 2 -quart saucepan, combine remaining 1 tablespoon butter, the butterscotch chips and corn syrup. Cook over medium heat until chips are melted, stirring constantly. Remove from heat. Stir in nuts. Spread mixture evenly over base. Bake for 10-15 minutes more until edges are bubbly.