Cut the ends off the onions and peel. Put the onions in a saucepan and pour in the chicken stock. Bring to a boil, then turn down to simmer for about 10 minutes. You want the onions to be barely tender. Remove the onions with a sleeved spoon (those spoons with holes in them) so that the stock remains in the pan.
Keep the stock simmering while you bring forth a frying pan. Melt the butter and stir in the flour (make sure the flour is thoroughly moistened - this prevents lumps later). Quickly add in the liquid ingredients (including the stock), stir constantly over a medium heat while then adding spices - except nutmeg (honestly, you don't need three hands to accomplish this maneuver).
Place the onions in a casserole dish (you might have done this when removing them from the stock). Pour the cream sauce over the top - sprinkle the bare bit of nutmeg on top of all. Place casserole dish in 375 degree oven for about 40 minutes. You can even brown the top slightly under the broiler if you wish and don't already have several other items to worry about.