Start by making the meatball sauce. Heat a tablespoon of olive oil in a frying pan over a medium-high heat, add the onions and origanum and gently fry until soft and translucent. Stir in the garlic and sauté for an additional minute.
Spoon half the onion mixture into a large bowl and set aside to cool.
Add the tomato paste, balsamic vinegar, tomatoes, chipotle paste, sugar and beef stock to the frying pan with the onion mixture, season well with salt and pepper and bring to the boil. Reduce the heat and gently simmer on a low heat for about 15 minutes or until the sauce has thickened.
Pre-heat the oven to 200°C/390°F.
To make the meatballs, place the minced beef, origanum, regular breadcrumbs and beaten egg into the bowl of cooled onions. Using your hands, combine the ingredients and generously season with salt and pepper.
Form the minced beef mixture into approximately 30 small meatballs. Heat a large frying pan on a medium-high heat, pour a few tablespoons of olive oil in the pan and fry the meatballs in batches for approximately 5 minutes or until they are golden brown all over.
Transfer the meatballs to the sauce and simmer for 15 minutes whilst the polenta is cooking.
Heat the chicken stock in a medium saucepan until almost boiling and slowly add the polenta constantly whisking until combined.
Reduce the heat to low, cover and cook for 15 minutes, whisking every 5 minutes. Then stir in the milk, butter, parmesan cheese and season to taste with salt and freshly ground black pepper.
Spoon the polenta into a +-25cm greased dish and top with the meatballs and sauce. Sprinkle over the mozzarella, parmesan cheese and panko breadcrumbs and bake in the pre-heated oven for 10 minutes or until the cheese is melted and the crumbs are golden. Garnish with parsley before serving.