Butter a 20x30cm baking dish. In a large saucepan, melt the butterscotch chips with the peanut butter, stirring frequently until smooth. Stir in the crispy rice cereal. Press half of the cereal mixture into the bottom of the prepared tin.
In the top of a double boiler, melt chocolate chips and butter together, stirring occasionally. Mix in icing sugar and water, and stir until smooth. Spread the chocolate mixture evenly over the cereal layer in the tin. Top with the remaining cereal mixture and press down lightly. Cover and chill for about 1 hour before cutting into squares.
Are also known as butterscotch morsels and can be purchased online.