We've picked up a pie from Rosati's two times now - both sausage and both quite delicious.
The sausage is ground, but has a lot of flavor.
The pie is sliced into little squares - which my husband, from Chicago, LOVES.
The do deliver, but we like to go for a little ride and pick it up. The place is in an odd kind of out-of-the way strip mall off of 116th. There are a couple of tables there, nothing fancy, it's clean (one thing you kind of worry about with delivery only places).
The gal at the front counter both times has been very nice.
Highly suggest you give this place a try!