Any heavy doughs, many cakes, and most cookies should be prepared using the Cookie Paddles. The recently introduced cookie paddles works wonderfully well for all but the stiffest cookie dough. These are strong and easy to clean.
If you already have a metal whip driver, get MUZ6CP1
If you have a plastic whip driver, you need to get a metal one to use the paddles. The paddles that come packaged with the driver are an excellent value.