Prepare the Chilies: Remove stems and seeds from the dried chilies. In a dry skillet, toast them lightly until fragrant, then soak in hot water for about 20 minutes.
Cook the Chicken: In a large pot, heat olive oil over medium heat. Add the chicken thighs and brown on all sides. Remove and set aside.
Sauté Aromatics: In the same pot, add the chopped onion and garlic. Sauté until soft and translucent.
Blend the Sauce: Drain the chilies and add them to a blender along with the almonds, raisins, sesame seeds, cinnamon, cumin, black pepper, tomato paste, and a cup of chicken broth. Blend until smooth.
Combine: Pour the mole sauce into the pot with the onions and garlic. Add the browned chicken thighs and the remaining chicken broth. Bring to a boil, then reduce heat and simmer covered for about 45 minutes, until chicken is cooked through.
Finish with Chocolate: Stir in the chopped dark chocolate until melted and well combined. Adjust seasoning with salt to taste.
Serve: Serve the Chicken Mole hot, accompanied by rice or warm tortillas.