Place potatoes in a Dutch oven; cover with water. Bring to a boil. Cover and cook over medium heat for 12-15 minutes or until potatoes are almost tender, adding the cabbage during the last 5 minutes of cooking.
Meanwhile, in a small saucepan, combine green onions and milk. Bring to a boil. Reduce heat; simmer, uncovered, for 5-6 minutes or until onions are soft.
Drain potato mixture. Mash with milk mixture, butter, salt and pepper.
This recipe was tested with Land O'Lakes light stick butter.