In a mixing bowl, cream butter, sugars and peanut butter. Add egg and vanilla; mix well. Combine flour, oats, baking soda and salt; stir into the a greased 13-in. X 9-in. X 2-in baking pan. Sprinkle with chocolate chips. Bake at 350 degrees for 20-25 minutes or until lightly browned. Cool 10 minutes. Combine icing ingredients; drizzle over bars. Yield: 3-4 dozen