Place cauliflower, potatoes and a big pinch of kosher salt in a large pot and add enough water to come just below the top of the vegetables.

Bring to a boil over high heat and then lower to a simmer. Cook until tender, about 15 minutes.

In the meantime, heat a large skillet over medium heat. Add the butter and scallions to the skillet and sauté for 1 minute. Add the kale, 3/4 cup water, and season with a pinch of salt. Cook until kale is tender and all of the water has evaporated, about 10 minutes.

Drain cauliflower and potatoes and transfer to the bowl of a mixer fitted with the paddle attachment. Season with 1/2 teaspoon salt and process until it forms a chunky puree. Stop the mixer. Add the cooked kale mixture and mix until just combined. Taste for seasoning.

Transfer colcannon to a serving dish. Form a well in the center of the mixture and add a Tablespoon of butter. Garnish with chives and serve.