Momofuku's Milk Bar in NYC. These are my favorite but the compost cookie and the cereal milk soft serve with cornflake crunch toppings are so good too.
By the way, David Chang is the chef/owner of all the Momofuku restaurants. He is such an amazing and innovative chef. Before you grab these desserts, make sure you go to the Ssäm Bar and try the steamed pork buns. They're insanely delicious. I can't wait to try all of his restaurants one of these days.