In Response to Re: Got a Question for VeryBestBaking? Ask it Here!:
Posted by Debra M
Since the chemical composition of some of the ingredients are not the same today as they were 30 years ago, a few minor changes had to be made. For example, water was eliminated because the quality of baking soda has improved over the years and no longer requires water in order to react (the water served as a catalyst). It is essentially the original recipe and any differences in the recipe (or method of preparation) reflect only the nature and chemical properties of the ingredients that are available today versus 30 years ago.
We do have a variation from our test kitchens that will give you a puffier cookie.
Just reduce the butter to 1/2 cup and add a 1/2 cup of solid vegetable shortening.