Cook potatoes and shallots in a large pot of boiling salted water until potatoes are tender, about 25 minutes. Drain, reserving 1 cup of the cooking liquid. Return potatos and shallots to the same pot. Meanwhile, stir 1 1/2 cups cheese (set aside remaining 1/4 cup) and half and half in a heavy small saucepan over medium heat until smooth. Add cheese mixture and cayenne to potatoes. Mash until smooth and fluffy, adding enough reserved cooking liquid to thin to desired consistency. Season with salt. Can be made 2 hours ahead. Cover; let stand at room temperature. Rewarm over low heat, stirring. Transfer to bowl. Top with green onions and remaining Cheddar cheese. Posted to FOODWINE Digest 16 Dec 96 Recipe by: Laura Hunter From: Laura Hunter Date: Tue, 17 Dec 1996 07:56:03 -0500