Lightly grease a 8x8 or 9x9 square pan and set aside. Melt butter and peanut butter in large pan over medium heat, stir until combined.
Add in 5 cups mini marshmallows, leaving 1 cup aside for later. Stir the mixture until the marshmallows have melted into the butter and peanut butter completely.
Remove from heat. Add in rice krispies and give them a quick stir to coat them in peanut butter. Add in the remaining marshmallows, then stir in the chocolate chips last.
Transfer to the prepared pan and use the back of a spatula to firmly flatten the mixture into the pan. Let cool and set completely before slicing.
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Notes
Doubling Instructions: Double all ingredients and use a 9x13 dish.Marshmallows: Large marshmallows can be used instead of mini ones.Peanut Butter: Any nut butter will work fine as a substitute!Storage Instructions: Once completely cool, slice the chocolate peanut butter rice krispies into 12 bars. Keep in an airtight container for up to 3 days.You can also place the squares in a freezer safe container for up to 2 months, allowing them to thaw at room temperature when ready to enjoy.