Prepare a 2-quart baking dish with parchment paper lined in the bottom and sides.
In a medium bowl mix together peanut butter, coconut sugar, coconut oil, and vanilla until smooth. Add in the oat flour and sesame seeds, and stir with a spatula until combined. You may have to finish mixing with your hands.
The batter should be similar to cookie dough. Then press it into the glass baking dish and smooth it with a spatula.
Make the chocolate layer by adding the semi-sweet chocolate chips to a small a microwave-safe bowl and microwave at 30-second intervals until it’s completely melted.
Pour the melted chocolate over the peanut butter layer and smooth it over the peanut butter layer entirely with a spoon.
Top the chocolate with chopped pecans.
Place in the freezer for 30 minutes or in the fridge for 1 hour before slicing into squares.
Take the bars out of the freezer and leave them for a couple of minutes before cutting. Then slice the bars into 12 even slices.
Store covered in the fridge until ready to eat. Bars will keep for up to two weeks.