To prepare the original Moroccan chicken tagine start rubbing the chicken inside and out with salt and pepper and set aside.
Remove the flesh and seeds from the salted lemons.
Rinse the rind and pat dry, then chop roughly and set aside.
Heat the butter and oil in a flameproof roasting dish, add the onions and garlic and cook until translucent.
Add the ginger, saffron and 2 cups water and mix well.
Season with salt and pepper.
Add the chicken and turn several times, until it is coated in sauce on all sides.
Bring to the boil, add the potatoes, cover and simmer gently for 45 minutes, turning the chicken frequently so that it absorbs the sauce evenly.
Add a little more hot water during cooking if necessary.
Stir in the olives, lemons, cilantro and parsley, cover and simmer for a further 20-25 minutes. Season to taste.
When the chicken is cooked, take it out, cover and keep warm.
If the sauce is too thin, boil over a high heat to reduce it slightly.
Carve the chicken and arrange on a warmed platter.
Top with olives and pieces of lemon rind and pour the sauce over.
Put the lid on the tagine and serve immediately.