I made a triple batch of the cookie recipe and the dough came out soft and workable. A key to making a tender shortbread style cookie (no egg) is to cream your butter and sugars until they are almost at the “whipped” stage, like whipped cream, and having lightened a couple of shades from were you started. You want the sugar to dissolve as much as possible. Sugar is hydroscopic so creates your “wet” component. Then, when adding your flour, incorporate gently and thoroughly, but just to the point it is incorporated. If you beat it too much, you will develop gluten and toughen the resulting cookie. Another tip for the buttercream: sift your confectioners sugar and use your whisk attachment if using a Kitchenaid. You will get a wonderful, smooth icing for piping. I only needed a double batch of icing for a triple batch of cookies. Good luck and happy baking!