In a saucepan over medium heat, melt the butter and brown sugar together. Add the marshmallows in and stir until smooth.
Pour over the popcorn and stir to coat evenly. Cool slightly before adding candy so it doesn't melt.
Add the M&M’s and sprinkles and toss gently until evenly distributed. Reserve some candy to add to the top of popcorn after you spread it out.
Spread in a single layer on a parchment paper lined cookie sheets to set up completely.
Place into festive containers to give as gifts or enjoy yourself!
Notes
Use fresh popcorn. Stale popcorn won’t hold up well once coated in the warm marshmallow mixture. Air-popped or lightly salted popcorn works best. I have also used microwave popcorn.Avoid burning the marshmallows. Melt the butter and marshmallows over low heat and stir constantly until smooth and glossy.Mix gently. When combining the popcorn with the melted marshmallow mixture, fold carefully so you don’t crush the popcorn or pretzels.Add candy last. Stir in M&Ms and sprinkles after the mixture has cooled slightly so the colors don’t melt or bleed.Work quickly. The marshmallow coating firms up fast—have all your mix-ins measured and ready to go before melting.Customize it! Add in a dark chocolate drizzle, chocolate chps, crushed candy canes, or holiday-themed cereal or other candy for fun flavor twists.