Some specialty or natural foods stores carry shelled pistachios in bulk, which makes cooking with them cheaper and easier on the fingers than having to shell them at home.
Coating with Nuts
Arrange the ground nuts in an 8-inch square on a sheet of waxed paper. Gently roll a log of chocolate cookie dough across the nuts.
Making Filling
Gradually beat the powdered sugar and milk in small amounts into the cocoa-margarine mixture, alternating sugar and milk until the mixture is creamy and ready to spread.