In mixing bowl, with mixer, beat yams or sweet potatoes until smooth. Mix in remaining yam casserole ingredients, beating until mixture is light and fluffy. Butter a 12 inch porcelain quiche dish or a shallow 2 quart casserole (7 x 11 inches). Pour in yam mixture, smoothing top evenly. Make praline topping by mixing all ingredients together in small bowl. Spread evenly over yams. May be refrigerated covered overnight at this point. Bake at 350 for 45 to 50 minutes or until golden brown and bubbly. Remove from oven and let stand 10 minutes before serving. Serves 10 to 12
Notes from the cookbook: The most sensational yam casserole I ever had was served to me one Thanksgiving by Alan and Barbara Shefter in Washington, D.C. Thanks to the Shefters, my family, friends and classes have been loving it ever since. The yams are fluffy and creamy, and the praline topping is sweet, nutty, crunchy, and beautifully glazed. If you want more of this delectable casserole, double the recipe but make it in two separate casseroles so that the proportions of the filling to the topping remains correct. Sweet potatoes can be used instead of yams.
Source: Marlene Sorosky's Year round Holiday Cookbook