Heat the olive oil in a large skillet or Dutch oven over medium-high heat. Add the chicken pieces and cook until browned on all sides. Remove the chicken from the skillet and set aside.

Add the chopped onion to the skillet and cook until softened, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.

Stir in the diced tomatoes (with their juice), rinsed black beans, and chicken broth. Bring the mixture to a simmer.

Add the chili powder, cumin, and cayenne pepper (if using). Season with salt and black pepper to taste. Return the browned chicken to the skillet.

Reduce the heat to low, cover, and let it simmer for at least 20 minutes, or until the chicken is cooked through and the sauce has thickened slightly. Stir occasionally.

Before serving, stir in the shredded cheddar cheese until melted and creamy. Taste and adjust seasonings if needed.

Serve hot over cooked rice or quinoa, garnished with fresh cilantro and a dollop of sour cream or Greek yogurt, if desired.