Preheat the oven to 350 F and line 2 baking sheets with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, mix the tahini, butter, brown sugar and granulated sugar, and beat until combined.
Add in eggs, one at a time, and vanilla extract, and mix until everything is well blended.
In a separate bowl, whisk together the dry ingredients - bread flour, all purpose flour, cinnamon, baking soda, baking powder and salt.
Add the dry ingredients to the wet mixture. Beat until combined.
Mix in the oats.
Fold in the chocolate chunks and pecans (if using!)
Cover wit plastic and refrigerate for at least 30 minutes.
Using a cookie scoop or your hands, scoop out the dough and gently roll into balls. Place onto lined baking sheets.
Press the balls down a bit, so that the top is a little flat, and add a piece of dark chocolate on top.
Bake for 12 minutes. Remove from the oven and allow to cool on baking pan for 5 minutes, before transferring to cooling rack.
Sprinkle with sea salt and enjoy!