
Preheat the oven: Position a rack in the center of the oven and preheat to 375°F. Line 2 large baking sheets with parchment paper.
Combine the dry ingredients: In a medium mixing bowl, whisk together flour, salt, baking powder, and cinnamon.
Combine the wet ingredients: In a large mixing bowl, combine the tahini, sugar, and brown sugar. Use a hand mixer to beat the ingredients together for about 1 minute; it will look crumbly like wet sand. Add eggs, cold water, and vanilla extract. Beat for 2 minutes until well-incorporated; the mixture should be smooth and fudgy.
Combine the wet and the dry ingredients: Add the flour mixture to the wet ingredients and beat on low speed for about 2 minutes until you only see a few streaks of flour. Swap the hand mixer for a rubber spatula, add the chocolate chips and mix to combine. The batter is thick and sticky.
Scoop the cookies: Scoop heaping 1 tablespoon cookie dough onto the prepared baking sheet. Arrange each cookie 2 inches apart. Wet your fingers (or the back of a spoon) and gently press the cookie mounds down just to even them out a bit. You still want them to be thick, you’re just pressing down the dome part a little. Dust with additional cinnamon.
Bake: Bake on the middle rack for about 10 minutes (see note). Let the cookies cool for a minute before transferring to a wire rack to cool.