In a large microwave-safe bowl, melt the peanut butter and chocolate chips together in the microwave, stirring every 30 seconds until smooth.
Once melted, stir in the crispy rice cereal and mini marshmallows until well combined.
Using a small cookie scoop or spoon, drop rounded mounds of the mixture onto a baking sheet lined with parchment paper.
Sift powdered sugar over the cookies to coat them lightly.
Allow the cookies to set at room temperature or in the refrigerator until firm.
Once set, the avalanche cookies are ready to be enjoyed!