The recipe is here.
Yes, you can have a negroni in a double old fashioned glass with ice, but it is also acceptable to serve it shaken in a chilled cocktail glass. I think it is prettier this way, well, until I got some classy new double old fashioned glasses a few weeks ago. But this is an old photo.
We both love it. This is an absolute classic cocktail and with good reason. This drink started Dave on a love affair with Campari which he is using a lot when making up cocktails.