First start by creaming the butter, brown sugar and granulated sugar together using a paddle attachment until fluffy. Add in the egg yolk and mix just until incorporated.
Add in the tahini paste, vanilla and the salt and mix until fluffy again. Add in both the whole wheat flour and the all purpose flour, the baking soda, and the baking powder. Mis until just combined. Add in the chocolate chips and fold those in.
Using a small cookie scooper, scoop out 14 equal cookie dough balls and place them on a parchment lined baking sheet or an airtight container and chill for 2 hours or overnight.
When it is time to bake the cookies, preheat the oven to 350F and line a large baking sheet with parchment paper or a silicone mat. Place the cookie dough call onto the baking sheet making sure to leave 1 1/2 - 2 inches of space between each cookie. Bake the cookies for 9-10 minutes.
When the cookies are out of the oven flatten them a little using a fork ( or keep them mounded. This totally depends on your preference) Top with sea salt and let the cookies cool for 10-15 minutes and then serve!