Combine the ground beef and cold water in a large pot or Dutch oven, breaking the meat apart with your fingers or a whisk until it is very fine and uniformly dispersed. Add the finely chopped onion (for the sauce) and kosher salt.
Bring to a gentle simmer over medium heat, stirring occasionally and skimming any foam, 10–15 minutes.
Stir in the tomato sauce, tomato paste, minced garlic, chili powder, ground cinnamon, ground cumin, ground allspice, ground cloves, dried oregano, cayenne pepper, bay leaves, and black pepper until evenly combined.
Reduce heat to low and simmer uncovered, stirring occasionally, until the chili slightly thickens but remains pourable and spoonable, 1 hour 30 minutes to 2 hours. Add a splash of water if it gets too thick.
Stir in the unsweetened chocolate, apple cider vinegar, Worcestershire sauce, and brown sugar. Simmer 15 minutes more. Remove and discard the bay leaves, then skim excess fat. Taste and adjust seasoning.
While the chili finishes, cook the spaghetti in salted boiling water until al dente, then drain well. Warm the canned kidney beans in a small saucepan with a splash of water until heated through.
To serve: 2-way = spaghetti topped with chili. 3-way = add a mound of finely shredded cheddar cheese. 4-way = add finely chopped onion. 5-way = add warmed kidney beans. Serve oyster crackers and hot sauce at the table.