Meanwhile, in small bowl, mix frosting and remaining 1 teaspoon maple extract until smooth. In another small bowl, mix peanuts, toffee bits and 1/2 teaspoon salt. Spread frosting evenly over cooled bars. Sprinkle with peanut mixture; press in lightly. Refrigerate about 30 minutes before cutting. Cut into 4 rows by 4 rows. Store covered.