This beautiful pomegranate dessert is served to celebrate Yalda, the Iranian celebration of the winter solstice. Think of masghati as a cross between Jell-O and panna cotta. It's infinitely more refined and delicate than Jell-O and not quite as wobbly as panna cotta. Prepare pomegranate masghati a few hours in advance, and serve chilled out of the fridge for a light and refreshing dessert.