Ingredients:

1 stick unsalted butter, room temperature
1/2 C tahini, well stirred
1 C sugar
1 large egg
1 egg yolk
1 t vanilla
1 C plus 2 T all-purpose flour (or matzo cake meal if making for Passover)
1/2 t baking soda
1/2 t baking powder
1 t kosher /sea salt
1 3/4 C dark chocolate chips or chunks (about 2/3 bag  of a 12oz bag of chips)
Flaky salt or coarse sea salt

Preparation:

Cream butter, tahini and sugar at med speed till light and fluffy, about 5 mins.
Add egg, egg yolk and vanilla and continue mixing for 5 more mins.
Mix flour, bs, bp, salt in a bowl; add to butter mixture and mix at low speed until just combined.
Fold in chocolate chips. Dough will be soft, not stiff. refrigerate at least 12 hrs – this ensures tender cookies.
Heat oven to 325 deg. Line baking sheet with parchment.
Make balls with 2 T of dough. Will make about 20-25 balls.
Place dough at least 3″ apart, bake 13-16 mins or until just golden brown around the edges but still pale in the middle to make thick, soft cookies.
As cookies come out of the oven, sprinkle sparsely with salt.
Let cool on wire racks.