Amy you have completely misread the last 30 minutes of Goodfellas. The prominence of the making of the food and the brother in the 3rd act has absolutely nothing to with Henry Hills relationship to them. It is merely meant to show his state of mind. That it is jarring to the audience is precisely the point. The film isn't trying to say he goes out of his way to pick up his brother and make him his favorite meal amid all the craziness because of some great love or loyalty. He's out of his mind on drugs, he shouldn't even leave the house. The fact that stirring sauce and trafficking guns and drugs is given the same weight by the narrator is insane and that's the point!! He has lost the ability to tell the difference between the mundane and ultra serious parts of the story he is telling. These things had only been shown in background up until now because they were incidental to the story. They still are but he's so off the rails there is no difference in his mind. This is exactly the way that someone that coked out would tell it. It's actually brilliant.