The scene in ‘The Godfather’ where Peter Clemenza makes spaghetti sauce was added in case the movie was a flop!
The idea was that if the movie was a flop, people would at least know how to make spaghetti sauce!
The scene where Clemenza makes spaghetti sauce is in the original novel, but the actual recipe is not.
In the movie, though, Clemenza gives the recipe while he cooks.
The DVD commentary explained that the recipe came from Francis Ford Coppola, the director.
He said that in case the movie flopped, at least people would know how to make spaghetti sauce.
Specific measurements aren't given, but if you pay attention, you can tell how much of each ingredient Clemenza uses in the scene.