When in the center of Princeton we just skip dessert and head for Halo. Their ice cream beats all desserts on offer. Wide selection, fast service even when the lines reach to the door. They also serve good coffee. Sit down (there is a small section next to the main area with seating and ice cream cakes) or take out. Cash only!
The decor is that of an English pub which, even after over a decade I find a little odd.