In a medium saucepan, mix together pudding mix and milk. Stir continuously and bring mixture to a boil, when mixture should thicken. Remove from heat and allow to cool to room temperature (you can continue stirring to speed up this process).
While pudding cools, melt the chocolate in a small microwave safe bowl or in a small pot.
Once the pudding has cooled, in a large bowl, gently fold together the whipped topping, pudding, and chocolate, until combined. (Now would be a good time to test the mixture -- you may prefer to add more chocolate for a more intense chocolate flavor).
Divide the mixture between two prepared pie crusts.
In a small bowl, combine peanut butter and flaxseed until smooth. Drizzle over the top of the pies. Swirl with a knife to create a design, if desired.
Top with additional chocolate chunks or chopped peanut butter cups, if desired.
Cover pies with a lid that does not touch the pies’ surface. Chill pies in freezer for 4-6 hours before serving.
Notes
Natural peanut butter seems to work best to easily drizzle over the pies, but most types of nut butters should work!
If your nut butter mixture doesn’t drizzle easily, you can heat the mixture in the microwave for 15-30 seconds to loosen the consistency.
If you prepare the pies the day before serving, you can remove them from the freezer about 30 minutes before serving to make cutting into them easier.
For extra chocolate and peanut butter flavor, line the bottom of the pie crusts with unwrapped peanut butter cups!