In a large skillet over medium-high heat, brown the ground beef with the diced onion and minced garlic. Break up the meat as it cooks using a wooden spoon. Cook until the beef is no longer pink, about 6 to 8 minutes. Drain any excess fat.

Add the cooked beef mixture to your 6-quart slow cooker. Add the kidney beans, black beans, corn, diced tomatoes, tomato sauce, beef broth, diced bell pepper, chili powder, cumin, smoked paprika, salt, and pepper. Stir everything together until well combined.

Cover the crockpot with the lid and cook on LOW for 6 to 8 hours, or on HIGH for 3 to 4 hours. The longer cooking time allows all the flavors to meld together beautifully. Stir occasionally if you're home.

About halfway through cooking, taste the soup and adjust the seasonings if needed. Add more chili powder for heat, salt for depth, or a pinch of sugar if the tomatoes taste too acidic.

Ladle the hot soup into bowls. Top with fresh cilantro, shredded cheese, sour cream, and crushed tortilla chips as desired. Serve with warm cornbread or crackers on the side.