Preheat oven to 325°F. Using a stand mixer, beat the butter, tahini, granulated sugar, brown sugar, sea salt and extracts on medium speed for 2 to 3 minutes, until fluffy. Scrape down the sides and add the egg and yolk. Mix for another minutes. Scrape down the sides. Add in the flour and baking soda on low speed, just until combined. Add in the chocolate chips and mix until combined.
Press dough into a 12-inch cast-iron skillet. (Our cast iron skillet was 8 inches so we scooped out ten Tablespoon-sized cookies from the batter and baked them as individual cookies so as to not pile up too much dough in the skillet.)
Bake for 20-25 minutes. Check after 17 minutes. The dough should be brown along the edges and pulling away from the sides. The cookie rose a bit at the edges and was flatter and a bit gooey in the center. We cut them into wedges and served them warm with vanilla ice cream. Pizookie!