Cook the Ground Beef: In a large skillet, cook the ground beef over medium heat until browned. Drain any excess fat.
Sauté Aromatics: Add the diced onion, minced garlic, and bell peppers to the skillet. Cook for 3-4 minutes until softened.
Combine in Crockpot: Transfer the beef and vegetables to the crockpot. Add the diced tomatoes, tomato paste, black beans, kidney beans, broth, chili powder, cumin, smoked paprika, cayenne pepper (if using), salt, and pepper.
Stir and Set: Mix everything thoroughly. Cover and cook on low for 6-8 hours or on high for 3-4 hours.
Adjust Seasoning: Taste and adjust the seasoning before serving.