Brown the meat by heating a large skillet over medium heat. Add ground beef and diced onion, cooking for 5-7 minutes until browned. Stir in minced garlic and cook for an additional minute. Drain excess grease.

Transfer the beef mixture to the slow cooker, scraping in any browned bits from the skillet. Set slow cooker to LOW for 6-8 hours or HIGH for 3-4 hours.

Combine rinsed canned kidney beans, black beans, diced tomatoes, tomato sauce, and beef broth in the slow cooker. Stir well to mix all ingredients.

Sprinkle chili powder, ground cumin, smoked paprika, dried oregano, cocoa powder, salt, and black pepper over the mixture. Mix thoroughly with a wooden spoon.

Cover the slow cooker lid and let cook on LOW for 6-8 hours or HIGH for 3-4 hours until chili thickens and meat is tender.

Serve hot, adding desired toppings like shredded cheese or jalapeños.