Heat a large dutch oven or soup pot over medium heat. Add a tablespoon of olive oil to the pan and then add the onion and garlic. Lower the heat to medium low and cover pot. Cook, stirring as needed until the onions are translucent and just starting to caramelize. This takes about 30 minutes.
Add the chicken, ancho chili powder, smoked paprika, ground cumin, onion powder, garlic powder, brown sugar, chipotle chilies and adobo sauce to the pot and continue to cook for an additional 10 minutes covered so that the chicken gets infused with the aromatics and the spices.
Stir in the chicken broth, diced tomatoes, beans (if using), and green chiles. Stir in the dark chocolate cocoa powder. Add salt and pepper to taste. Bring to a slow boil and cook, uncovered, stirring as needed until the liquid has reduced to your level of preference.
For serving, pass the cotija cheese and chopped cilantro for topping as desired.
This is great with beer bread and a salad.