Add onion and saute 3 minutes, then add garlic and saute 30 seconds longer. Pour onions into a 6 or 7 quart slow cooker.
Return skillet to medium-high eat, add beef and cook stirring occasionally until beef has browned.
Stir in diced tomatoes, tomato sauce, beef broth, chili powder, cumin, paprika, cocoa powder, sugar, coriander and season mixture with salt and pepper to taste.
Stir in dark and light red kidney beans and allow to heat through, about 2 minutes. Serve warm with desired toppings.