Mrs Cromwell's Cookbook was published in 1664, long after the "Commonwealth" under Oliver Cromwell, with an intention to discredit the Cromwells as having been unsuited to run the country.
There is a copy in the Cromwell Museum in Huntingdon. Stuart Orme, the Curator of the Museum, has recorded a brief introduction for Talking of Food, together with a selection of the recipes in the book. It's notable that the recipes don't give cooking times and other details which we expect in modern cookbooks.
To give you an idea of the acerbity of the essays, here is the very beginning of the Introductions:
TO THE READER
THAT there may no prejudice lye against this Publication, as an insultory, unmanlike Invective and Triumph over the supposed miserable and forlorn estate of this Family, and this Person in particular; it will be requisite to obviate & prepare against the seeming humane (but indeed disloyal, or at least idle) sentiment and reverence to the frail and fluctuating condition of mankind, which us a general Argument is ready at hand to oppose the design of the ensuing Treatise.
Not to refer the Reader to the practise of all Times, which have not failed to wreak the fury of the Pen upon Tyrants and Usurpers (if surviving to punishment, otherwise their Relations and Posterity) whole execrable Tragedies have wearied the World, and blunted the Instruments of death & slaughter: nor to instance the particular examples thereof, as sufficient Authority for this Imitation; the peculiar Justice due to the monstrous enormities and unparalle’ld insolence of these upstarts, (besides the disproportion and incompetence of any revenge to their provoking impudent personation of Princes) will interessedly vindicate and defend the Author from the breach of charity, much more from the rigid imputation and charge, as of a person devested and void of nature, compassion and civility.
If you really want to try any of the recipes Stuart has read, you can find them here, but, even better why not purchase a copy of the new reprint of Mrs Cromwell's Cookbook which is available from the Museum website.
Stuart has also recorded a short video on the cookbook.