Step 1: Boil the Potatoes

1. Place potatoes in a large pot and cover with salted water.
2. Bring to a boil, then reduce heat to medium-low and simmer for 15 to 20 minutes until tender.
3. Drain and set aside.

Step 2: Cook the Cabbage

4. While the potatoes are boiling, simmer or steam cabbage in a separate pot until tender.
5. Drain, chop, and keep warm.

Step 3: Cook the Leeks in Milk

6. Place leeks in a small pot and add just enough milk to cover.
7. Simmer over low heat for about 3 to 5 minutes, or until leeks are soft.

Step 4: Mash and Mix

8. Mash the cooked potatoes with salt, pepper, and ground mace.
9. Stir in the leeks with their cooking milk.
10. Fold in the chopped cabbage, mixing until the potatoes turn pale green.

Step 5: Add the Butter and Serve

11. Make a well in the center of the colcannon and pour in the melted butter.
12. Mix well and serve hot.