01 -
In a large saucepan over low heat, melt unsalted butter and peanut butter together, stirring frequently until combined and smooth.
02 -
Add mini marshmallows to the saucepan and stir continuously until they are fully melted and incorporated into the mixture.
03 -
Remove the saucepan from heat, then gently fold in the crispy rice cereal until it is evenly coated with the marshmallow mixture.
04 -
Transfer the mixture to an 8x8-inch pan prepared with butter or non-stick spray, and press it evenly but gently to avoid compacting the bars.
05 -
Allow the bars to sit at room temperature for at least 2 hours to firm up before cutting and serving.