Add to a kettle the onion, butter, nutmeg, pepper. Cook on medium and mix together and stir. Once melted add flour. Mix in and cook for 3 mins on med-high heat. This is your rue (this looks like the texture when your making gravy) after all done, pour in all heavy whipping cream. Stir with a wisk and bring to a hot boil. Boil for about 10 mins. It should look like a gravy. Don't burn keep whisking! Once done set aside. Place potatoes in a deep baking dish ( I just use the disposable silver pan). Spread them out evenly. Now pour your mixture over your potatoes. Gently toss them. if you like alot of onions you can add more onions across the top and then pepper some more. Cover with foil and bake on 350 for 2 hours. You can check them as you like. You want the taters nice and soft. Once done you remove them. They will be nice and brown around the edges but be careful not to burn them!