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, and cloves. Cook for 1 minute.
4. Add the cocoa powder, beef broth, tomato sauce, vinegar, Worcestershire sauce, brown sugar, salt, and pepper. Stir well.
5. Bring the mixture to a boil, then reduce heat and simmer uncovered for 2 hours, stirring occasionally.
6. Serve the chili over cooked spaghetti. Top with shredded cheddar cheese, diced onions, and kidney beans.