Cool dessert place, hmmm. Nothing comes to mind but you could just amble through Randolph st and find different places to eat and drink. There's a place in south loop called Decadent Dessert Bar but not sure you'd spend 2-3 hours there. There's Eataly, which also exists in NYC and Vegas and a few other places (Maybe DC)? I think you really could pick any neighborhood in Chicago and just walk around for a while. Wicker Park, Old Town, Lincoln Park, West Loop, Downtown/lakefront, etc.