Now widely believed to be extinct, the imperial woodpecker was once the largest woodpecker on the planet. It’s a mystery as to exactly how that bit of ornithological history inspired Neesa Peterson to leave behind a career in New York fashion to open a New Orleans sno-­ball shop in the West Village. But luckily for New Orleanians, after three summers she decided to return to her childhood home to continue her contribution to local sno-­ball tradition.

While the list of flavors includes sta...