You achieve the domed shape of these buttery peanut butter shortbread cookies by using a small ice-cream scoop. The dough is tender and soft, and your hands won't work nearly as well as the scoop. Purchase one at a kitchenware store, and then you will have it when the urge to make these calls, which could be often. (The scoop should be 1 ½ inches in diameter.) Like almost anything made with peanut butter, these are resoundingly popular.