Colcannon - cooking recipe

Ingredients

2 lbs baking potatoes, peeled and thinly sliced
8 ounces parsnips, peeled and thinly sliced
2 medium onions, thinly sliced
1/2 medium cabbage, finely shredded (coarse outer leaves removed and reserved)
2 1/2 cups boiling water
1/4 cup unsalted butter (1/2 stick)
1 1/2 teaspoons salt
1/4 teaspoon fresh ground pepper
1 -2 tablespoon milk (optional)

Preparation

Arrange 1/3 of potatoes over bottom of heavy medium saucepan.
Layer on 1/3 of parsnips, 1/3 of onions, and 1/3 of shredded cabbage; repeat layers twice more.
Pour in water, cover tightly with reserved cabbage leaves.
Cover and simmer until vegetables are very tender, about 1 hour; discard whole cabbage leaves.
Drain mixture in a large sieve or small-holed colander; return vegetables to saucepan.
Add butter, salt and pepper.
Mash until fluffy, adding milk if dry.