There were two major adjustments made to the cookies this time. The first is the whipping of the butter. The texture of the cookies depends largely on the butter. The butter has to be whipped to be more fluffy, and to whip the butter to the ideal degree, you have to soften it completely. I'm an impatient person, and when I've made cookies before, I've always waited for the butter to soften completely before whipping it. In that case, the butter could not be beaten to the desired level of puffiness, thus affecting the texture of the finished product. The correct approach, should be to cut the butter into smaller pieces, put at room temperature to soften, soften to the surface can be easily pressed down a pit, it means that the butter softened well!
The second is the use of fine gauze sugar and powdered sugar, I used to use only one kind, granulated sugar or powdered sugar! And actually adding both fine sugar and powdered sugar is to balance the ductility of the cookie dough. Cookies with only powdered sugar will have too little ductility and the cookies will not be fluffy enough, while cookies with only fine granulated sugar will have too much ductility and the finished product won't have a clear enough pattern.