If you find yourself in a situation where you're getting ready to make tahini brownies and realize you're out of brown sugar, you can either substitute white granulated sugar, or just make some brown sugar. To make brown sugar, add a tablespoon of unsulphured molasses to a cup of white granulated sugar. Stir the sugar and the molasses until the sugar is completely coated. I usually do this in a sealed zip-top bag, using my fingers to rub the molasses into the sugar from the outside of the bag.