Brown the meat (optional but recommended): In a skillet over medium heat, cook the ground beef with onion and garlic until no pink remains. Drain excess fat. (If you want a more traditional Cincinnati chili texture, don’t brown — just crumble it raw into the slow cooker.)
Layer in the slow cooker: Add beef (browned or raw), tomato sauce, crushed tomatoes, broth, chili powder, cinnamon, cumin, paprika, allspice, cloves, cocoa powder, salt, vinegar, and brown sugar. Stir to combine.
Cook low and slow: LOW: 6–8 hours; HIGH: 3–4 hours. Stir once or twice if you can.
Add beans near the end: Stir in the kidney beans during the last 20–30 minutes of cooking. This gives them plenty of flavor but keeps them firm and kid-friendly.
Adjust seasoning: Taste before serving — add salt, a dash more vinegar, or sugar if needed to balance sweet, savory, and spice.