Portillo’s has launched a new dessert based it one of its most popular — and most iconic — menu items, thanks to a new collaboration from a famous New York bakery. Portillo’s and Milk Bar, the famed New York dessert shop soon coming to the West Loop, launched a limited edition “Chocolate Cake Cookie” Tuesday, according to a press release. The new treat features the flavors of the restaurants moist chocolate cake and fudge frosting, baked into a Milk Bar cookie.