I ought to be reassured by Richard Corrigan writing “there’s no such thing as a recipe for colcannon really,” but all he’s doing in The Clatter of Forks and Spoons is dismissing the need for exact measurements or debating whether you can substitute kale for Savoy cabbage. The great chef is not jettisoning the spuds, bedrock of this rustic Irish classic.

Both colcannon and its country cousin champ can be made using fresh or leftover potatoes, but they have to be the floury sort, boiled in their skins. The texture is all wrong with waxy varieties. Parsnips can be added but mustn’t be a puree.

The champ mash variant is proof, though that dishes mutate with the times. Originally it was made with stinging nettles – peasant stuff indeed – but over the years spring onions, green and white parts, became the norm. The word colcannon is from the Gaelic term cal ceannann, which means white-headed cabbage while cainnenin can mean garlic, onion, or leek.

But does all this looseness give me carte blanche to make colcannon with mashed celeriac, albeit kept deliberately lumpy? After all, the Scots equivalent of an avenue for leftover mashed potatoes, rumbledethumps, can easily incorporate swede or turnip, while England’s own bubble and squeak has licence to use up a whole gallimaufry of fridge remnants.

In this company, celeriac is a class apart, especially when the mash (never a puree) is augmented with cream and butter, then stirred into lacy Savoy and young leek, braised but retaining a certain bite. Oh and I couldn’t resist adding crisp pancetta to the mix. I call it my Colcannon Royale.

It would have made a fine bowlful on its own, but I partnered it with an old school coq au vin, which made for a testingly rich lunch. Before I had a much-needed lie-down I continued some cursory research into the role of colcannon in Irish life and its curious association with Halloween.

Indeed the first written mention was a 1735 diary entry of one William Bulkely, a traveller from Wales who had the dish on October 31 in Dublin: “Dined at Cos. Wm. Parry, and also supped there upon a shoulder of mutton roasted and what they call there Coel Callen, which is cabbage boiled, potatoes and parsnips, all this mixed together. They eat well enough, and is a dish always had in this kingdom on this night.”

Bulkely didn’t know the half of it. For Halloween the Celts developed their own souped up fortune telling equivalent of coins in Christmas pud. It all kicked off with a blindfolded spinster plucking from the garden the head of cabbage or kale that is to be cooked in the colcannon.  

Charms were mixed into the dish itself. Which charm you found was seen as a portent for the future. A button meant you would remain a bachelor and a thimble meant you would remain a spinster for the coming year. A ring meant you would get married and a coin meant you would come into wealth.

To seal the deal unmarried women would stick the first and last spoonfuls of Halloween colcannon into a stocking and hang it on their doors. Guaranteeing the first man who walked through the door would become their husband.

There’s even a 19th century folk song, ‘The Skillet Pot’ that celebrates the dish:

“Did you ever eat colcannon when ’twas made with yellow cream,
And the kale and praties blended like the picture in a dream?
Did you ever take a forkful, and dip it in the lake
Of the heather-flavoured butter that your mother used to make?”

Time to consult Alan Davidson’s Oxford Companion To Food, one of the greatest books in the English language. An immediate surprise in the colcannon entry is its adoption by the English upper classes in the late 18th century. According to one account: “A more elaborate mash was prepared of potatoes and Brussels sprouts, highly flavoured with ginger and moistened with generous amounts of milk and butter.” Now that is a ‘Royale rival’.

Still for those lower down the social ranks it is so often a leftover dish. And I’ve still got three quarters of a Savoy cabbage and half a bag of Rooster potatoes. Onions, garlic and chorizo are yanked from the larder, chicken stock from the freezer and soon, small world, a big pot of Portuguese Caldo Verde is simmering on the hob. Shall we call it Sopa de Colcannon’?