Heat the olive oil in a large tagine, Dutch oven, or heavy-bottomed pot over medium-high heat. Season the chicken thighs with salt and pepper, then sear them for 4-5 minutes on each side until golden brown, then remove and set aside.

In the same pot, reduce the heat to medium and add the chopped onion. Sauté for about 5 minutes until the onion becomes soft and translucent, scraping up any browned bits from the bottom of the pan.

Stir in the minced garlic, grated ginger, turmeric, cumin, and cinnamon. Cook for another 1-2 minutes until the spices are fragrant and coat the onions evenly.

Return the chicken to the pot and arrange the sweet potato chunks and carrot slices around and on top of the meat. Pour in the chicken broth, ensuring the liquid covers the bottom of the pot but doesn't completely submerge the vegetables.

Bring the liquid to a gentle boil, then reduce the heat to low, cover the pot, and simmer for 45-50 minutes. The chicken should be cooked through and the vegetables tender when pierced with a fork.

Stir in the green olives during the last 5 minutes of cooking to warm them through. Taste the sauce and adjust the seasoning with more salt or pepper if needed.

Remove from heat and garnish generously with fresh chopped cilantro. Serve hot directly from the pot with a side of steamed couscous or warm flatbread.