Preheat the oven to 350F/180C.
Brown the chicken breasts in 1 tbsp of olive oil in a large, deep pan for approximately 5 minutes on each side. Remove and set aside.
4 chicken breasts, 1 tbsp olive oil
In the same pan, sauté the onions for 5 minutes, then add the garlic and cook for another minute.
1-2 garlic cloves, 1 medium onion
Add the turmeric, curry powder, smoked paprika, mustard powder, cinnamon, and salt to the pan. Stir to combine.
1 tbsp turmeric, 1 tbsp curry powder or curry paste, 2 tsp smoked paprika, 1 tsp mustard powder or prepared mustard, 2 tsp cinnamon, Salt to taste
Return the chicken to the pan and add the chicken stock, black olives, preserved lemons, and butternut squash. Lightly stir and bring to a boil.
1 cup/250 ml chicken stock, 6-8 black olives, 4 slices of preserved lemons, 2 cups/700g butternut squash
Cover the pan with a lid and cook in the preheated oven for 20 minutes. Then, uncover and cook for an additional 15 minutes.
Be careful not to overcook the chicken breasts, as they can become dry.
Serve the chicken tagine with couscous or rice.