1. In a large pot, brown the ground beef over medium heat. Drain excess fat.
2. Add the chopped onion and minced garlic to the pot. Cook until the onion is translucent.
3. Stir in the chili powder, cinnamon, cumin, allspice, cloves, salt, and black pepper. Cook for 1 minute.
4. Add the cocoa powder, beef broth, tomato sauce, apple cider vinegar, Worcestershire sauce, and brown sugar. Stir well.
5. Bring the mixture to a boil, then reduce the heat to low. Simmer uncovered for 2 hours, stirring occasionally.
6. If using, add the kidney beans in the last 30 minutes of cooking.
7. Serve the chili over spaghetti and top with shredded cheese, diced onions, and oyster crackers if desired.