Cream butter sugar and vanilla until light and fluffy.
Sift together the flour & baking powder.
If you like, these can be served without frosting or just make a half batch of frosting if you prefer less.
Note: the amount of leavening agents has been reduced from the original measurements first published in this recipe years ago. That's based upon reports of the cookies falling in the centre when baked.
I have omitted the baking soda completely and reduced the baking powder by 1/4 tsp. This has worked very well in my experiments with this recipe and with those who tested it for me.
These freeze exceptionally well in sealed plastic containers.