Mishti Doi is a sweet yogurt dessert that is popular in Kolkata. It is made by boiling milk and then adding a culture of yogurt to it. The mixture is then sweetened with sugar and left to ferment overnight. The end result is a creamy and sweet yogurt with a slightly tangy flavor. Mishti Doi is often served chilled and is a refreshing dessert option after a spicy meal. It is a must-try for those with a sweet tooth.