Heat the oil in a very large pan and fry the onion and garlic until it begins to soften. Add the chili, coriander, cumin, and crushed cardamom pods and stir well.
Add the peppers then break up the ground beef into the pan and, using a fork, keep turning it to separate it as the meat browns. Add the chopped tomatoes, ketchup, tomato puree, and water stirring to make a rich red sauce. When the chili starts to boil sprinkle over the cocoa and stir it in. Add the beans and simmer partially covered for 1 1/2 hours. At this point you can cool and freeze the chili, or just keep it in the refrigerator overnight.
Preheat the oven to 425 degrees F.
Pour the chili into a large, wide dish or keep in the pan you cooked it in if it is ovenproof.
Combine the salt, cornmeal, flour, baking powder, and cinnamon in a bowl. Whisk together the buttermilk, eggs, honey, and oil in a jug, and then stir into the dry ingredients mixing to make a vivid yellow batter.
Pour the cornmeal topping over the chili con carne, or blob it over to cover the top as evenly as possible.
Sprinkle the cheese over the top of the cornbread and then bake in the oven for 30 minutes or until the cornbread topping is risen and golden and the chili underneath is bubbling. How long this takes depends on the how cold or hot the chili was when it went into the oven. Since it's such a huge vat, you may find it easiest to reheat it on the stove in its pan first.
Let the chili stand for about 5 minutes once out of the oven before cutting the cornbread top into squares or slices to serve with a helping of chili underneath.
Mash the avocados with the scallions and add the juice of up to 2 limes, to taste. Stir in most of the cilantro and turn into 2 bowls, sprinkling each with the remaining cilantro.
Divide the sour cream into another 2 bowls, and dust with a little paprika and, into another pair of bowls add the grated Cheddar so that people can take clumps and add the tangy cheese to their plates of guacamole and sour cream splodged chili.
Recipe courtesy of Nigella Lawson(Copyright 2004, Feast, Hyperion, All Rights Reserved)