Line a 8x8 pan with parchment paper or tinfoil.
In a food processor or blender, place the flax seeds and pulse for 10-15 seconds until they are broken down. Add in the oats and pulse for another 5-10 seconds to break down the oats. You want them about half their original size. Set mixture aside.
In a large stock pot, over medium-low heat melt the nut butter, honey and coconut oil, stirring frequently. Remove from heat, and add in the peppermint extract, stirring to combine. Let cool for 10-15 minutes or until just barley warm to touch.
Add in the oat mixture and stir until well combined. Add in the chocolate chunks and stir until combined.
Transfer the oat mixture to the pan and press down until you have an even layer of oats. I find placing my hand inside a plastic sandwich bag then pressing down the mixture helps it from sticking to the oat mixture. Press down hard and evenly until the mixture will not press down any more.
In a small microwave safe bowl, add the chocolate chips and coconut oil and heat in 30 second intervals until the chocolate is melted, stirring after each interval.
Drizzle the chocolate on top of the granola bars or if you want a thick layer, simply pour the chocolate over the entire pan and spread into a thin layer with a knife or spatula.
Place the pan in the fridge and let set for 2 hours. Cut into 18 bars or small bites and serve.