Heat a large pot on medium with a few tablespoons of olive oil. Add the onions and cook until translucent a couple of minutes. Add the minced garlic, carrots and butternut squash and cook with the lid on to soften the veggies about 10 min. Then add the bell pepper, Serrano peppers, diced tomatoes with their sauce and tomato paste.
At this point you can add as much of the 4 cups of broth as you want depending on the thickness you desire.
Add the cocoa powder, cinnamon, bay leaf, coriander, paprika, cayenne pepper, chili powder, oregano, cumin, and salt and pepper.
Bring to a boil, then reduce heat and simmer for at least 1 hour, or until the beans are tender.
Remove the bay leaf before serving. Garnish with your favorite toppings.