Another huge favorite from the kitchen of Jim's mom. Many versions of this casserole exist under many different names... but we bet this one's the best! May be prepared a day ahead.
Peel and grate cold potatoes into large bowl (or pour bag of frozen potatoes into bowl). Heat soup and butter over low heat. Remove from heat and blend in sour cream and green onions. Pour sour cream mixture over cold potatoes in bowl and toss gently. Spread potato mixture in buttered 8x10x2-inch casserole. Sprinkle with crushed Corn Flakes, dot with butter. Bake uncovered at 350F for 45 minutes.