1Peel and cut rutabaga and potatoes into two inch pieces and put into separate saucepans. Cover with water. Add 1 teaspoon salt to each pan. Cook until tender, remove from heat and drain. Leave in pan. Rutabaga will take about 30 minutes, and potatoes will take less time (about 5 minutes less). Both are done when they are not firm when you jab them with a fork.
2Heat the milk. Mash the drained potatoes in the pan. Add all the hot milk and mash potatoes some more (adding the milk before the butter makes the potatoes smoother). Add 2 tablespoons butter. Mash some more. Taste and add more salt if necessary. Mash drained rutabaga in the pot in which they were cooked. Add 2 tablespoons butter and mash some more.
3Combine mashed rutabaga and potatoes; add pepper, and nutmeg. Mash some more. Taste and add more salt if necessary. If you wish, garnish with chopped parsley.