Add beef, in batches if necessary, and cook, breaking up with a wooden spoon, until browned.
Add chili powder, Worcestershire sauce, cinnamon, cumin, allspice, cloves, bay leaf, chocolate, beef broth, tomato sauce, cider vinegar, and red pepper. Stir to mix well. Bring to a boil. Reduce heat to low; cover and simmer 1 1/2 hours, stirring occasionally. Refrigerate overnight if possible.