Crack cake. That’s what the renowned sponge cake should be called at this 30-year-old Chinatown coffee counter, so criminally good, you’ll think it’s laced with something illegal. It doesn’t look like much—a squishy, boat-shaped white-sugar cake, pulled from the oven, wrapped in paper and hidden in Tupperware behind the counter. But its unassuming appearance belies an angel-food-like interior, ethereally light and mildly sweet. Even better? The shop has launched a green-tea variety, smaller than the original but steeped with earthy tea flavor, mellowing out to a vanilla finish.