Heat a large heavy-bottomed pot or Dutch oven over medium-high heat. Add the olive oil to the pot, swirling to cover the entire surface. Working in batches, sauté the chicken on each side until lightly browned, approximately 3-4 minutes. Transfer chicken to a large bowl. Sauté remaining chicken breasts, adding additional olive oil to the pot, as needed.
Return the chicken with juices back to the pot or Dutch oven. Add the chicken broth and orange juice to the pot and bring to a boil. Reduce heat to low, cover with a tight-fitting lid, and simmer until chicken is fully cooked. Approximately 25 minutes.
Carefully remove chicken to a clean bowl and set aside. Reserve broth for later use.
FOR THE SAUCE
Heat olive oil in a separate large and heavy-bottomed saucepan over medium-high heat. Add the onions and sauté until golden brown and just starting to caramelize, approximately 12 minutes. Stir frequently. Reduce heat to medium. Add the pumpkin seeds, sliced almonds, garlic, cumin seeds, coriander seeds, whole star anise, and whole cloves to the saucepan. Sauté for 1-2 minutes, until garlic becomes fragrant, stirring continuously.
Add the dried chiles to the pot and stir to combine. Sauté for approximately 2-3 minutes or until chiles start to soften.
Grab the reserved chicken and orange broth and carefully pour the liquid into the saucepan with the onion and chiles. Reserve pot for later. Add the cinnamon stick, bay leaves, raisins, marjoram, thyme, and oregano to the saucepan and mix well. Bring to a low boil, cover, and reduce to a simmer. Cook until chiles are very soft, approximately 30-34 minutes.
Stir in the tomato paste and cook for an additional 1-2 minutes. Remove from heat. Add the chocolate. Allow sauce to cool for 10 minutes and the chocolate to melt.
Working in batches, transfer sauce mixture to the bowl of a blender and process until smooth. Avoid overfilling. Transfer mixture to the reserved pot. Repeat until all sauce is processed. Season with salt and pepper, to taste.
PUT IT TOGETHER
Shred chicken and combine with approximately half of the sauce mixture. Add more sauce, as desired. Reserve remaining sauce for later use.
Best served warm with rice or warm tortillas and sprinkled with fresh cilantro and pumpkin seeds.
This recipe makes a lot of extra sauce. I recommend freezing the remaining sauce in small jars for later use. It tastes fantastic in enchiladas, burritos, rice casseroles, etc.