Preparation Cook potatoes in large pot of boiling water until tender. Drain well. Press through food mill or ricer into same pot or return to pot and mash. Mix in milk and 1 1/2 tablespoons butter. Melt remaining 1/2 tablespoon butter in heavy small skillet. Add green onions and sauté until wilted, about 1 minute. Add to potatoes. Add Parmesan and mix gently. Season with salt and freshly ground pepper and serve.