I read in Mark Forsyth's Etymologicon that Milton coined loads of words. That was great, until the list got to "cooking". I find it incredible that nobody stuck "ing" on the end of "cook" before Paradise Lost. The online etymology dictionary didn't have anything useful to say on the subject. Does anyone have a good source explaining the origin of this word, or the sense in which Milton coined it?
I don't think it's reasonable to consider the use of a participle or gerund as a fully new use (though it would still be well worth noting when such was first used).
Peter Shor's answer offers a genuinely new use: cooking not as a gerund or participle, but as a wholly separate noun, cooking the gerund refers to the act of cooking but cooking the noun refers to what is produced and shares meanings with both cookery ("I like her cooking") and cuisine ("I like French cooking").
But the quote we have from Milton is not about cookery. It is a metaphorical use of the gerund that became a common sense:
For God does not here preciſely ſay, I make a female to this male, as he did before; but expounding himſelf here on purpoſe, he ſaith, becauſe it is not good for man to be alone, I make him therefore a meet help. God ſupplies the privation of not good, with the perfect gift of a real an poſitive good; it is man's perverſe cooking who hath turn'd this bounty of God into a Scropion, either by weak and ſhallow conﬅructions, or by proud arrogance and cruelty to them who neither in their purpoſes nor in their actions have offended aginﬅ the due honour of Wedloc.
Here he is not speaking about food at all. He is talking about marriage—defending marriage, in fact. There has long been a controversy within Christian thinking; from scripture and elsewhere we can find both arguments in favour of married life and arguments in favour of complete celibacy and how then to best combine the two? Milton spends quite some time and ink on the topic, but at this point he is saying that what is bad in sexual relations comes not from God who created man and woman and the sexual attraction between them, but that man has altered and corrupted what was "natural" and from God, into something else.
Theological and sexual-political objections to that, aside, this is what he is talking about as man's perverſe cooking; not the literal act of using heat and admixture to turn one food into another, but a metaphorical widening in which it comes to mean turning one anything into another thing.
It is cooking as in, to manipulate, doctor, alter, falsify. Which sense I see is claimed as being 1630s by the etymonline.com but alas I don't have a full OED to hand to verify further.
We now have this sense as a fully separate sense, and would understand "cook the books" without having to consider the metaphor. So I offer that this was the coinage, born out of a metaphorical use by Milton, but then becoming a separate well-known meaning in its own right.
I suspect he refers to the noun (or gerund) , his cooking is awful, rather than the simple participle he is cooking. But either way,"somebody must have said it earlier" isn't evidence; the first written reference the OED can find is indeed from Tetrachordon, in 1645.
(Interestingly, they also cannot find a written reference for the transitive verb he cooks the meat before 1616, though there are earlier uses of the intransitive he is chosen to cook for the crew, apparently meaning 'to act as kitchen manager', from which the transitive form evolved)
Shakespeare used cookery rather than cooking as the noun for the verb cook.
Pompey. We'll feast each other ere we part; and let's
Draw lots who shall begin.
Antony. That will I, Pompey.
Pompey. No, Antony, take the lot: but, first
Or last, your fine Egyptian cookery
Shall have the fame. I have heard that Julius Caesar
Grew fat with feasting there.
Merriam-Webster says the word "cookery" dates to the 14th Century. So while Milton may have the first recorded use of the noun cooking, he used it to replace another perfectly good word for the exact same concept.
OED has this as the earliest citation:
1645 Milton Tetrachordon 8 : It is mans pervers cooking who hath turn'd this bounty of God into a Scorpion.
Note that this is cooking as a gerund/noun, not a present participle.
I went on a little expedition through the verse of Edmund Spenser, who wrote earlier than Milton. I couldn't find a single gerund. That doesn't mean that he didn't use them, but it does indicate that they weren't very common, and it may well be that that form only began to emerge in the seventeenth century. Milton may well have been the first to put it into print.