Line a 9x13 inch baking dish with parchment paper. Set aside.
In a large microwave safe bowl, melt the butterscotch chips and peanut butter in 30 second intervals, mixing until smooth. Mix in the rice krispies.
Press the mixture into the prepared baking dish. Cover and refrigerate until hardened.
In a microwave safe bowl, melt the chocolate chips and butter in 30 second intervals, mixing until smooth. Spread evenly over the bars.
Refrigerate until the chocolate is firm, then cut into squares.