In a sauce pan, melt together the peanut butter and maple syrup until well combined over medium heat.
Add the cheerios and popcorn to a large bowl. Gently mix to distribute. Pour half of the peanut butter mixture into the bowl and use a rubber spatula to help mix
Line a square baking pan with parchment paper and press the cheerio and popcorn mixture tightly into the pan.
In a skillet, melt the dark chocolate until it's smooth and thin.
Pour the melted chocolate over the cheerio mixture in an even layer.
Once the chocolate is set, take the bars out of the pan and flip them over. Take a sharp knife and slice into 8 rectangular bars.