Brown the beef. In a large skillet over medium-high heat, cook the ground beef (2 pounds), breaking it into bite-size crumbles, until well browned and no pink remains. Using a slotted spoon, transfer the beef to a 6-quart slow cooker. Leave about 2 tablespoons of the rendered beef fat in the skillet; drain off any excess.
Sauté the vegetables. Reduce the heat to medium. Add the onion (1) and red bell pepper (1) to the beef drippings and cook, stirring occasionally, until softened, about 5–7 minutes.
Add the garlic. Stir in the garlic (1 tablespoon) and cook until fragrant, about 30 seconds.
Build the flavor base. Add the tomato paste (2 tablespoons), chili powder (2 1/2 tablespoons), cumin (2 teaspoons), coriander (1 teaspoon), smoked paprika (1 teaspoon), oregano (1 teaspoon), black pepper (1/2 teaspoon), cayenne (1/4 teaspoon), cocoa powder (1 teaspoon), salt (1 1/2 teaspoons), and sugar (1 teaspoon). Cook, stirring constantly, for 1–2 minutes, until the tomato paste darkens slightly and the spices are fragrant. Do not let the spices scorch.
Deglaze with the broth. Pour in the beef broth (8 ounces) and scrape up the browned bits from the bottom of the skillet. Simmer for 1–2 minutes, stirring, just until everything is well combined. Pour the mixture into the slow cooker.
Add the remaining ingredients. Add the crushed tomatoes, diced tomatoes and their juices (2 cans), Better Than Bouillon (3/4 tablespoon), Worcestershire sauce (1 tablespoon), kidney beans (1 can), and pinto beans (1 can). Stir thoroughly, making sure the Better Than Bouillon is incorporated into the sauce.
Slow cook. Cover and cook on LOW for 5 hours. Stir well and check the consistency and flavor. Continue cooking for up to 1 additional hour, if needed, until the flavors are deeply developed and the chili has reached the desired consistency.
Check the consistency. The chili should be thick but saucy, with plenty of rich sauce surrounding the beef and beans. When tipped from a ladle, the beef, beans, and sauce should slide heavily together rather than releasing watery liquid or falling out in a dry clump. If the chili is too thick, stir in beef broth a few tablespoons at a time until the desired consistency is reached.
Taste and finish. Taste and adjust the salt and cayenne as needed. Cover and let the chili rest for about 10 minutes before serving.