Rub the chicken pieces in salt and pepper. Melt butter in a large, heavy skillet or stew pot, and add the chicken and onions. Cover and simmer over lowest heat, periodically adding stock until you have used it all. (If you don't have stock, use plain water or bouillon) After 15 minutes, remove half a cup the cooking liquid thin the peanut butter or paste. Add tot he pot and bring to a boil . Reduce heat and then whisk some of the hot stew liquid into the egg yolks. Add to the pot and stir incorporate the egg mixture into the stew. SImmer gently until chicken in done. Be Careful not to heat the stew above a simmer from this point. Garnish with parsley leaves and serve with rice or a corn porridge.