1. In a large skillet, brown the ground beef over medium heat. Drain any excess fat.
2. Add the chopped onion and minced garlic to the skillet. Cook until the onion is translucent.
3. Transfer the beef mixture to the slow cooker. Add the kidney beans, black beans, diced tomatoes, chili powder, cumin, paprika, oregano, salt, black pepper, and beef broth.
4. Stir everything together until well combined.
5. Cover and cook on low for 8 hours or on high for 4 hours.
6. Serve hot with your favorite toppings like shredded cheese, sour cream, or chopped green onions.
Notes:
For extra heat, add a chopped jalapeño or a pinch of cayenne pepper.