I'm going to make the beef ravioli recipe from Richard Olney's Simple French Food. One of the ingredients is marrow. I've never bought or cooked with it. So what am I looking for? I understand I'm asking a butcher for a bone, but do I need to specify the type of bone? And do I have the butcher cut it or do something to render the marrow accessible?
and if anyone has any experiences with making ravioli that I should know about, let me know.