Heat oven to 350°F. Grease bottom only of 13x9-inch pan. Prepare brownie mix as directed on package using oil, 3 tablespoons water and egg. Spread batter in greased pan. Bake at 350°F. for 17 to 22 minutes or until edges are set. DO NOT OVERBAKE. Cool 45 minutes or until completely cooled. Freeze brownie base for 20 minutes so filling is easier to spread.
In small bowl, combine 1 1/2 cups peanut butter and powdered sugar; blend well. Spread over cold brownie base.
In small saucepan, melt chocolate chips over low heat, stirring frequently. Add 1/4 cup peanut butter; mix well. Spread over bars. Sprinkle top with peanuts and candies. Score bars to make 36 pieces. Refrigerate 45 minutes or until chocolate is set. Store covered at room temperature. Cut on scored lines into bars.