Colcannon Soup 2 Tbsps. Butter 2 Leeks - (just white part), Trimmed and Chopped 4 Cups Diced Cabbage 3 Baking Potatoes, Peeled and Diced 4 Cups Chicken Stock 1 Cup Milk Salt and Pepper To Taste 6 Green Onions, Sliced Heat butter in a dutch oven. Add leeks and cook gently until just wilted. Add cabbage and combine well. Cook a few minutes. Add potatoes and Chicken stock. Bring to the boil. Simmer for 20 minutes,or until potatoes are very tender. With potato masher, gently mash some of the potatoes, so that the soup thickens. Stir in milk. Season with salt and pepper. Add green onions and cook 1 minute more.