01 - Heat a large skillet over medium-high heat. Add ground beef and cook until browned, breaking it apart with a spoon, until no longer pink. Drain excess fat.
02 - Add diced onion, red and green bell peppers, and minced garlic to the skillet with the beef. Sauté for 2–3 minutes until vegetables are slightly softened.
03 - Transfer the beef and vegetable mixture to a 5–6 quart slow cooker.
04 - Add kidney beans, black beans, diced tomatoes with their juices, tomato paste, beef broth, chili powder, cumin, smoked paprika, oregano, salt, black pepper, and cayenne pepper. Stir thoroughly to combine all ingredients.
05 - Cover and cook on low heat for 6–7 hours (or on high heat for 3–4 hours) until flavors have melded and chili is thickened.
06 - Taste the chili and adjust salt, pepper, or cayenne as desired. Serve hot topped with shredded cheddar cheese, sour cream, green onions, or fresh cilantro if desired.