Colcannon (Irish Mashed Potatoes With Cabbage)

An Irish favorite, colcannon combines potatoes and greens into a hearty mash. While in the US it’s become a mainstay for St. Patrick’s day celebrations, in Ireland it’s a dish deeply linked to and traditionally served on Halloween (although also enjoyed year-round). It’s the perfect partner for sausages and a pint of beer, but also just as good at the family dinner table as a side for corned beef or baked ham; crowned with a fried egg or some smoked salmon; or even alongside a simple green salad to complete a filling meal.

Colcannon emerged as a staple food in Ireland by the mid-18th century, according to Smithsonian Magazine. The name colcannon likely originated from the Gaelic phrase cal ceannann, which means "white-headed cabbage." Like many other Irish potato dishes, colcannon was created as a resourceful way to transform humble potatoes into a filling side dish using various available ingredients. In this vein, it was often made with whatever greens were on hand to supplement the potatoes—cabbage, broccoli leaves, kale, sorrel, watercress, or more. It’s a recipe that is as adaptable and frugal as it is delicious. 

In this recipe below, our Birmingham-based test kitchen colleague Jasmine Smith has created the richest, most hearty version possible. The key to making great colcannon is to start with perfectly boiled potatoes—all the better to soak up more butter and milk.

For the creamiest mash, Jasmine found that medium-starch yellow potatoes (such as Yukon Golds) worked best. Yellow potatoes have just the right amount of starch (less than starchy russets, but more than small waxy new potatoes) to ensure the perfect thick yet silky mashed texture. When cooked, the starch granules within the potato cells absorb water and swell, and some cells inevitably burst, releasing a gluey gel that helps give the mashed potatoes just the right amount of cohesiveness. Keep the potato chunks in large pieces so that they don’t become water-logged when boiled. 

While the potatoes may seem like the star of the show, colcannon’s flavor comes from the added butter, milk, and greens. We chose garlic and scallions to build an aromatic allium base before sautéing the cabbage. While we love cabbage for its neutral flavor and accessibility in this recipe, really you could substitute any preferred green, like kale or Swiss chard; just be sure to still fully wilt whatever green you choose before folding them into the potatoes.

On top of the classic alliums and cabbage, though, we sneak in another (optional) ingredient: seaweed. While seaweed isn’t traditional in colcannon, we like it for the subtle vegetal umami depth it adds to the mash. Plus, seaweed has been used in Irish cooking for centuries. In her cookbook From Forgotten Skills of Cooking, Darina Allen points out how many varieties of seaweed “have been part of the diet of coastal peoples since time immemorial.” In recent years it’s regained popularity with young Irish chefs.

While the seaweed is optional, we believe it’s what sets this version apart from so many others. Laver seaweed, sold in dried dark green sheets labeled as nori, is crisp, relatively mild, slightly saline, with roasted, smoky, nearly nutty notes. It pairs well with the hearty potatoes in this mash. To add it to the mash, we finely chop it and then steep it in the milk mixture until the seaweed is softened and the milk is infused with a briny, umami-rich flavor. 

Whether you add the seaweed or not, make sure not to forget to stud the top of the hot mash with pads of butter to melt and pool all over. It's the final step that guarantees these are potatoes you’re sure to love.