In the bowl of an electric mixer cream the butter, tahini and sugar together with  the paddle attachment until it is light and fluffy. It will look looser than when you are creaming just butter for cookies due to the tahini. 

Add the eggs and orange flower water and continue to mix until completely combined. 

Mix all of the dry ingredients together in a separate bowl to fluff and combine with a whisk rather than sifting them. 

Add all of the dry ingredients to the tahini egg mixture and mix on low just until combined without over mixing. Scrape the bottom of the bowl to incorporate any unmixed butter and stir in the chocolate with a rubber spatula. 

Line a baking sheet with parchment or a silpat and scoop the cookie dough with a 2 ounce ice cream disher onto the parchment. Don't worry about spreading them out, we will chill the dough before baking. Freeze or refrigerate over night. 

At this point you can bake all of the cookies now or place the frozen dough balls in a zip top bag and store them in the freezer for easy baking later. I like my cookies to be crisp on the outside and a little gooey on the inside, so I find that I like them when they are baked from frozen best.

When you are ready to bake the cookies place them on a parchment lined cookie sheet at least 3 inches apart and bake in a preheated 350 oven for approximately 8-10 minutes rotating half way through. Remember that cookies continue to bake on the cookie sheet after you pull them out so pull them from the oven a just before you think they are ready and keep a close eye on them.