In a large pot or Dutch oven, heat 1 tablespoon of olive oil over medium heat. Add the ground beef and cook until browned, breaking it up into small pieces as it cooks. Drain any excess fat if necessary, then return the beef to the pot.
Sauté the Vegetables:
Add the chopped onions and garlic to the pot with the beef. Sauté for about 5 minutes, until the onions become soft and translucent.
Add the Tomato Base:
Stir in the beef broth, tomato sauce, tomato paste, Worcestershire sauce, and apple cider vinegar. Mix until everything is well combined.
Season the Chili:
Add the chili powder, cumin, cinnamon, cocoa powder, allspice, salt, pepper, and brown sugar (if using). Stir everything together and bring the chili to a simmer.
Simmer the Chili:
Reduce the heat to low and let the chili simmer uncovered for at least 45 minutes to an hour, stirring occasionally. The chili should thicken and the flavors should meld together. If it gets too thick, you can add a little water or more beef broth to reach your desired consistency.
Cook the Spaghetti:
While the chili is simmering, cook the spaghetti according to the package directions. Drain the pasta and set aside.
Assemble the Cincinnati Chili:
To serve, place a portion of cooked spaghetti in a bowl. Ladle the Cincinnati chili on top of the pasta.
Top and Serve:
Top with shredded cheddar cheese, chopped onions, and a spoonful of kidney beans (if desired). For added heat, drizzle with hot sauce.
