A planned heating system (as earlier reported by Eater) was still under construction. Yet even windchill in the single digits couldn't hold back the Shack heads in Madison Square Park.

"I was here a half-hour ago," said the day's first customer, after ordering up a shack burger and chili fries at 12:06 p.m.

To stay? Or to go? I asked. "To go," she said. "I don't sit and eat here normally."

Two self-described bloggers were the next arrivals. How ironic, one commented, that even without the Shack's usual long lines, patrons still had to wait. (A gas issue, apparently, delayed the venue's scheduled 11:30 a.m. opening.)

A veritable line had, in fact, formed, by 12:20 p.m., however, when this reporter's buzzer went off (after ordering 12 minutes earlier).

In the frigid air, you could literally watch steam escaping from your burger. Carting a vanilla shake back to the office, I completely lost feeling in my fingers. But oh, so tasty.