There was something about the loftiness, the berriness, and the sugary crustiness of Jordan Marsh blueberry muffins that hooked Boston in the 60s. Jordan Marsh (“Jahduns”) was Boston’s answer to Macy’s for more than 150 years, until Macy’s had the final answer and acquired it in 1996. It speaks to the power of a good snack that a sugar delivery system for tired shoppers has become a favorite memento of this late, great New England retailer. The muffin’s originator, Jordan’s baker John Pupek, kept his recipe a professional secret. This triggered Muffin Mystery Mania, when home bakers and restaurants alike set out to recreate the oversized, overstuffed muffin. For decades, the media and the…