1. Chop the onions, mushrooms, and garlic. Drain and rinse the pinto beans and fava beans.
2. In a large pot over medium-high heat, cook the beef until browned, breaking it apart as it cooks. If there is a lot of fat, drain some off.
3. Add the butter to the pot. Stir in the onions, mushrooms, and garlic and cook for about 5 minutes, until softened.
4. Stir in the diced tomatoes, tomato paste, and beef broth.
5. Add the pinto beans and fava beans and stir well.
6. Add cumin, cayenne pepper (to taste), salt, pepper, and basil leaves. Mix everything.
7. Bring to a gentle boil, then reduce heat and let simmer for 30–40 minutes, stirring occasionally.
8. Taste and add more salt, pepper, or cayenne if needed before serving. 🌶️