Marshmallow donuts at the Fenwick Bakery on Harford Rd. (across from Mastellone's).
This is not something I would expect to like in the slightest but they are really quite fabulous. Beignet-like donuts stuffed with a very generous blob of marshmallow glop that is whipped up a bit and is not quite as sweet as you'd expect (not to say these aren't really sweet, just not CLOYINGLY sweet). Irresistable to kids from 5 to 105.
Call ahead to reserve some -- they go fast.