In the States, Colcannon tends to be served only once we start gearing up for St. Patrick's Day festivities, but it's actually a traditional Irish dish that is usually eaten in Ireland during the fall and winter. I usually reserve this dish for when we have company over, because it's a great flexible recipe that you can play around with and easily cater to your taste buds or to those of your guests. Add it to your list of great St. Patrick's Day recipes, along withcorned beef and cabbage!
Put the potatoes into a large pot, cover with water, and bring to a boil over medium heat. Salt the water and cook the potatoes until tender.

While the potatoes are cooking, heat extra virgin olive oil and butter in a separate saucepan. Once the butter starts to melt, add the onion and cabbage and cook on medium until they soften and caramelize, about 5 - 8 minutes.

Once potatoes are done (when they are tender), drain and return the potatoes to the hot pot. Add the Saga Bleu, the caramelized onions, the cabbage, and the milk. Toss to coat the potatoes (the mixture will look slightly mashed).
Stir in the lemon zest and season with salt and pepper, to taste.
Transfer to a serving bowl and serve!