I’m Donut?, a Japanese bakery chain known for its viral popularity and its curiously punctuated name, opened earlier this year in a sleek Times Square storefront. The company’s specialty is the nama doughnut (the word, in Japanese, means “raw,” or “fresh”), an impossibly moist and light cumulus of starch and sugar that seems captured by gravity thanks only to the marginal heft of various frostings, icings, and fillings. This textural sorcery is achieved by way of a proprietary yeasted dough whose recipe involves, among other things, kabocha squash, which introduces a bit of earthy sweetness and gives the interiors a sunny yellow hue. The brand’s “original” doughnut, a sugar-dusted, circular pillow without a hole in the center, is something of a miracle—breathy, yeasty, tender, and warm, it was the dream…