Pop microwave popcorn according to package directions. Spread popcorn in a single layer over a 13″x18″ sheet tray. Remove any un-popped kernels.
Melt 1 cup of semi-sweet chocolate chips in the microwave in 20-25 second bursts, stirring in between. When the chips completely melt down when you stir, continue stirring until there are no lumps left.
Use a fork to drizzle and dollop the melted chocolate over the popcorn, making sure to get the kernels along the edges and in the corners. Let chocolate set for appox 30-60 seconds.
Sprinkle mini-M&Ms across the chocolate drizzle so that they stick.
Transfer sheet tray into freezer or refrigerator for 20 minutes until chocolate has hardened, then break the popcorn into bite-sized pieces and flip them over on the sheet pan.
Repeat drizzling more chocolate and M&Ms over the back of the popcorn. Chill for 20 minutes, then break into pieces to serve.