Preheat oven to 400ºF.
Place a 12-inch cast iron skillet over medium high heat, add the ground beef in an even layer and cook until browned. Drain excess grease, leaving about a tablespoon. Add the onions, garlic, bell pepper, sweet potato and spices. Cook stirring occasionally, until the vegetables soften, about 3-5 minutes. Add the tomatoes, black beans and beef broth and bring to a simmer.
Place cast iron skillet on the center rack of the oven and bake for 35-40 minutes or until the sweet potatoes are nice and tender. Add shredded cheese and broil until cheese is melted and bubbling, about 2-3 minutes. Salt and pepper to taste; serve immediately and enjoy!
