1Heat oven to 350°F. In medium bowl, mix flour, brown sugar and salt. Cut in 1/2 cup butter, using pastry blender or crisscrossing 2 knives, until evenly mixed. Press evenly in bottom of ungreased rectangular pan, 13x9x2 inches. Bake 15 minutes; cool slightly.
2Cut up any large nuts. Sprinkle nuts evenly over crust. In 1-quart saucepan, heat all remaining ingredients over low heat, stirring occasionally, just until chips are melted. Drizzle butterscotch mixture evenly over nuts. Bake 5 minutes. For bars, cut into 8 rows by 4 rows while warm for easiest cutting.