Melt butter in medium pot over low heat. Add marshmallows and brown sugar. Stir until smooth, then remove from heat.

Lightly coat a large bowl with nonstick spray, and add popcorn, then drizzle marshmallow mixture over popcorn and stir.

Add Craisins and nuts, and toss with a spoon. Allow to cool slightly, then add M&Ms.

With buttered hands, form popcorn mixture into balls and place balls on a baking sheet covered in waxed paper.