Step 1: Sauté the Aromatics

1. Heat 2 tablespoons of olive oil in a large pan over medium heat.
2. Add the chopped onion, bell pepper, and carrot, sautéing until soft (about 5 minutes).
3. Stir in the minced garlic and cook for another minute, until fragrant.

Step 2: Brown the Beef

1. Add the ground beef to the pan and cook until browned, breaking it up with a spatula.
2. Drain excess fat if necessary, but leave a little for extra flavor.
3. Stir in the tomato paste, Worcestershire sauce, chili powder, cumin, paprika, oregano, and cayenne pepper. Let the spices toast for 30 seconds to enhance their flavors.

Step 3: Transfer to the Slow Cooker

1. Pour the browned beef mixture into the slow cooker.
2. Add the kidney beans, black beans, crushed tomatoes, diced tomatoes, beef broth, salt, black pepper, and cocoa powder.
3. Stir everything together to evenly distribute the ingredients.

Step 4: Slow Cook the Chili

1. Cover and cook on LOW for 6-8 hours or HIGH for 4-5 hours.
2. Stir occasionally if possible, allowing the flavors to blend.

Step 5: Adjust Seasoning & Serve

1. Taste the chili and adjust seasoning as needed (add more salt, chili powder, or broth if necessary).
2. Serve hot with cheese, sour cream, fresh cilantro, and tortilla chips or cornbread.