Heat oven to 350º. Grease bottom and sides of 13x9 pan.
Beat brown sugar, butter, peanut butter, vanilla and eggs in large bowl with electric mixer on medium speed until well blended. Stir in flour, baking powder, baking soda, and salt. Cut 12 of the candies in fourths. Stir in cut-up candies and chocolate chips into batter. Spread in pan.
Bake 25 to 30 minutes or until golden. Immediately press remaining candies into brownies in 4 even rows of 6 candies each. Cool completely. Cut into 6 rows by 4 rows.