In a large Dutch oven or heavy-bottomed pot, brown the ground beef over medium-high heat, breaking it up with a wooden spoon, about 8-10 minutes. Drain excess fat if needed.
Add diced onion and bell pepper to the beef. Cook until vegetables are softened, about 5 minutes. Stir in garlic and cook for 1 more minute.
Add tomato paste and stir well, cooking for 2 minutes to deepen the flavor.
Pour in crushed tomatoes, diced tomatoes, and beef broth. Stir to combine.
Add both types of beans, chili powder, cumin, smoked paprika, cayenne pepper, and brown sugar. Season with salt and black pepper.
Bring to a boil, then reduce heat to low. Cover and simmer for 30 minutes, stirring occasionally.
Taste and adjust seasonings as needed. Serve hot with your favorite toppings—don't skimp on the cheese and sour cream!