How to Make It
Place popcorn, raisins, cranberries, peanuts, and pistachios in a large bowl.
Melt butter and marshmallows in a large saucepan over medium-high. Cook, stirring often, until smooth, about 6 minutes. Meanwhile, coat a 13-by-9-inch baking dish with cooking spray.
Pour marshmallow mixture over popcorn mixture and stir until thoroughly combined. Scrape mixture into baking dish; press firmly into an even layer. Let stand until firm, about 30 minutes. Cut into 12 bars.