In a large skillet over medium-high heat, brown the ground beef and diced onion until beef is no longer pink, about 5-7 minutes. Add minced garlic and sauté for 1 more minute.

Drain any excess grease from the skillet and transfer the beef mixture to your slow cooker.

Add rinsed kidney beans, black beans, diced tomatoes, tomato sauce, and beef broth to the slow cooker. Stir gently to combine.

Sprinkle in chili powder, ground cumin, smoked paprika, dried oregano, cocoa powder, salt, and black pepper. Stir thoroughly.

Secure the lid and cook on LOW for 6-8 hours or HIGH for 3-4 hours.

Give the chili a good stir before serving and ladle into bowls. Top with garnishes like shredded cheese or sour cream if desired.