Baskin Robbins and its 31 flavors has been around for a long time. It has never tried to be fancy, which is one reason we like its ice cream cake. It's good, basic, reasonably priced, and ready for pick up any time. One particular favorite is the mint chocolate chip ice cream and oreo combo. B-R will decorate a cake on request.
The store has franchises everywhere, though recently a number have consolidated, changed hands, or just plain shut down, so you might do well to call ahead.