Fill a large pot with cold water, adding a pinch of salt. Peel and cut the Yukon Gold potatoes into evenly sized pieces, then place them in the pot. Bring to a boil over high heat, then reduce to a simmer for 20 minutes until fork-tender.

Melt 2 tablespoons of Irish butter in a large skillet over medium heat. Add 4 cups of chopped cabbage and sauté for 5-7 minutes until soft and vibrant. Stir in 2 cups of chopped spring onions and cook for an additional 2-3 minutes, then remove from heat.

Drain the potatoes and return them to the pot. Mash until smooth and fluffy, ensuring no lumps remain.

Fold the sautéed cabbage and spring onion mixture into the mashed potatoes. Pour in ½ cup of warm whole milk and mix for a rich consistency. If desired, sprinkle in 1 cup of Irish cheddar cheese, gently folding until creamy.

Taste and add salt as needed. Serve warm, pairing with corned beef or your favorite protein dish.