Use mixers to combine the creamy peanut butter and melted butter until smooth.
Add the powdered sugar and mix again until combined.
Add the rice krispies and mix until just combined. Be sure not to over mix the rice krispies as the batter will become too sticky to work with. It should easily press into the pan.
Press the rice krispie peanut butter batter into the lined 8 by 8 baking dish. Spread it out into an even layer.
Melt the chocolate chips with peanut butter together in the microwave. Microwave in 20-30 second increments, stirring each time, until smooth.
Spread the melted chocolate over the top in an even layer. Use a spoon or rubber spatula to spread it out evenly.
Refrigerate the bars until firm and the chocolate is set. Cut into 12 squares and store in an airtight container in the refrigerator or freezer.*
Notes
*Leftover peanut butter rice krispie bars can be stored in an airtight container in the refrigerator for 3-5 days, or in the freezer for 1-2 months.