I take it you are referring to the paragraph where Swift finally presents his idea, based on the report of an American of "his acquaintance." It is actually the eighth paragraph in my book, but it could be that you have a slightly different edition.
What is important to note is the way that the series of modifiers after the word "food" in this paragraph move this shocking idea to being one that is completely hilarious through a long list of different ways in which an Irish child can be cooked. Consider how Swift achieves this:
I have been assured by a very knowing American of my acquaintance in London, that a young healthy child well nursed is at a year old a most delicious, noruishing, and wholesome food, whether stewed, roasted, baked, or boiled, and I make no doubt that it will equally serve in a fricassee, or ragout.
Swift uses exaggeration here to highlight the immense humour of what he is suggesting. In addition to proposing cannibalism, he then goes on to list a number of different ways in which the children can be consumed, going as far as presenting himself as something of a food expert, not merely restricting himself to common ways of cooking, but also mentioning such methods as creating a "fricassee, or ragout." Swift is obviously increasing the satire of his suggestion by pretending to present an Irish child as the latest "must-have" food and suggesting a number of different ways that it could be consumed. To suggest the idea of canniballism itself would be shocking enough, but then to go on and identify a number of different ways of preparing the Irish child for consuming makes it even more shocking.