Line 2 large baking sheets with parchment paper.

In a large microwave safe bowl, heat chocolate chips and sweetened condensed milk on high power for 1 minute; stir. If needed, continue to microwave at 15 seconds intervals until chocolate is just melted and smooth. (You don't want your chocolate to be too hot, or the marshmallows will melt!).

Stir in the peanuts, followed by the marshmallows. Drop spoonfuls of the mixture onto the prepared baking sheets. Refrigerate until firm.