Melt butterscotch morsels with peanut butter in heavy saucepan over very low heat, stirring constantly until well blended. Remove from heat.
Add KELLOGG'S RICE KRISPIES cereal to butterscotch mixture, stirring until well coated. Press half of cereal mixture into 8 x 8 x 2-inch pan coated with cooking spray. Chill in refrigerator while preparing filling. Set remaining cereal mixture aside.
Combine chocolate morsels, powdered sugar, butter and water. Stir over very low heat until chocolate melts and mixture is well blended. Spread over chilled cereal mixture. Spread remaining cereal mixture evenly over top. Press in gently. Chill. Remove from refrigerator for about 10 minutes before cutting into squares.