Beat in sugar, a little at a time, to form a stiff dough that is no longer sticky. This is a very heavy dough and I burned out a small hand mixer the first time I made it, so if using a mixer be sure it is heavy-duty.
Form dough into 1" balls, place on wax paper and flatten to form patties.
Let patties dry at room temperature 2 hours, turning once.
In medium saucepan over low heat, melt chocolate chips and shortening, stirring often. I recommend using a double boiler if you have one, since it's easy to scorch if you aren't careful.
Lay patties on the tines of a fork and dip into melted chocolate. Let cool on wax paper until set, at least 30 minutes.