Place bay leaf, allspice, and cloves in the center of a cheesecloth square. Bring up corners of cheesecloth, tie closed with kitchen string, and set aside.

In a large skillet (or using the saute function on your slow cooker) cook ground beef over medium heat until browned, using a wooden spoon to break up meat as it cooks. Drain off fat. Transfer meat to a 4-quart slow cooker. Stir 1 cup onions, tomato sauce, the water, chili powder, garlic, Worcestershire sauce, cumin, cinnamon, salt, and cayenne pepper into meat in cooker. Stir in spice bag.

Cover and cook on low for 8 to 10 hours or on high for 4 to 5 hours, stirring in chocolate during the last 30 minutes of cooking. Warm kidney beans in a separate pot, or, if everyone wants beans, stir them into the chili with the chocolate.

To serve, remove spice bag. Spoon chili over hot cooked spaghetti. Sprinkle each serving with chopped onions and cheese.