Preheat oven to 350˚F and line a baking sheet with parchment paper.
Whisk flour, baking soda and salt together in a mixing bowl until evenly distributed. Set aside.
In a large bowl with an electric mixer, cream butter, sugar and brown sugar until light and fluffy, about 2 minutes.
Mix in tahini, egg and vanilla extract and beat until smooth.
Add flour, about 1/2- 3/4 cup at a time, until combined, scraping sides as needed.
Add 2 tablespoons sesame seeds and chocolate chips and mix until combined.
Mix remaining sesame seeds together in a small bowl.
Scoop 2 tablespoons of dough and roll into balls. Dip in sesame seed mixture to coat.
Transfer dough balls to the prepared baking sheet a few inches apart. Bake cookies for 13 - 15 minutes or until cookies have slightly golden edges and the centers are set.
Remove from oven and allow the cookies to cool for a few minutes before transferring to a cooling rack.