In a large bowl, combine the chicken with olive oil, unsalted, room-temperature butter, garlic, and all the spices except for the saffron. Mix well and let marinate for up to one hour.
Preheat a Tagine pot on medium-low heat for 3-5 min. A Dutch oven, aka cocotte, may be used instead of the Tagine pot, and another alternative is a cast-iron skillet with a lid.
Put in the chopped onions and a drizzle of olive oil, and stir. Add the chicken mixture and sauté for 5 minutes. Next, flip the chicken and sauté for five more minutes. The chicken should be browned and the onions translucent. Add the saffron and 1/4 cup hot water, cover, and cook for 15 minutes.
Check the water level and stir the chicken. Add more hot water if the chicken sticks to the pot and the sauce is too thick. Add only a little, or the sauce will be too runny. 1/4 cup more should be just enough for the chicken to cook. Place the preserved lemons over the top and cook for 15-30 minutes, until the meat is fully cooked and the sauce is slightly thick.
Throw in the olives and chopped parsley, reduce the heat to low, and let simmer for 5 min.
Serve your Tagine hot and top it off with French Fries for a beautiful crisp. Serve with Fresh Moroccan mint tea and some bread on the side. You may serve your chicken on a bed of oven-roasted potatoes as a healthier alternative. Please see the notes below for the recipe.
For a keto version, skip the bread and the French fries and pair your dish with unsweetened iced tea.