M&S 40p Fresh Market Specials offer also includes 1.5 kilos of Chopin potatoes, a kilo of carrots, 500 grams of parsnips and a single broccoli head.
And, according to a newspaper advert, the fresh veg deal also featured a whopping "500kg" bag of sprouts.
M&S bosses blamed it on a misprint.
An M&S spokesperson said: “We aim to deliver value, but clearly this is a misprint and we’re sorry for any confusion caused.”
M&S confirmed a 500g bag of Brussels sprouts is available for 40p. The supermarket also advertises the Fresh Market Specials on their website which includes a 500g bag of sprouts.
M&S would not actually be expected to provide that amount of sprouts, according to the Advertising Standards Authority (ASA).
An ASA spokesman said: "It seems like a situation where it is a simple mistake and consumers would likely recognise this too.
"No doubt the advertiser would immediately rectify it and it is unlikely we would expect the advertiser to provide that amount of sprouts."
A 500 kilo bag of sprouts would also feed the entire British armed forces who cook up half a tonne of sprouts each Christmas along with 4.8 million sausages, 3,000 turkeys and 1.3 million potatoes, according to Defence Equipment and Support.