In a large skillet over medium-high heat, brown the ground beef, breaking it up with a spoon, until fully cooked. Drain off any excess fat.

Transfer the cooked beef to your slow cooker.

To the same skillet, add the diced onion and bell pepper. Sauté for 4-5 minutes until softened. Add the minced garlic and cook for 1 more minute, then transfer this mixture to the crockpot.

Add the drained kidney beans, pinto beans, crushed tomatoes, tomato sauce, and beef broth to the slow cooker.

Add all the spices: chili powder, cumin, smoked paprika, oregano, cayenne (if using), salt, and black pepper. Stir everything thoroughly until well combined.

Cover and cook on LOW for 6-8 hours or on HIGH for 3-4 hours.

Taste and adjust seasoning with more salt or spices if needed before serving.