For the chicken stock, put all the stock ingredients in a large saucepan. Cover with cold water and slowly bring to the boil. Reduce the heat and simmer for 3 hours. Skim off any fat from the surface, the more fat you remove, the clearer, and therefore purer, your stock will be.
Strain the stock through a sieve lined with a fine cloth. Slowly pour it through - don’t press or it will become cloudy. Pour the strained stock into a clean saucepan and simmer until the volume of liquid has reduced by half. Strain again and chill.
For the onion jam, heat the olive oil in a saucepan. Add the onions and bay leaf and cook gently until soft. Cook over a low heat for about an hour, or until the onions are golden-brown and their natural sugars have caramelised. Remove from the heat. When cool, place in a airtight container and transfer to the fridge.
To make the ricotta, heat the milk until just below boiling, then add the salt and lemon juice. Remove from the heat and set aside for 10 minutes. After this time, the milk should be curdled. Strain through a muslin cloth and leave to rest for 30 minutes (leave for longer if you prefer a drier ricotta). Store in an airtight container and in the fridge.
Preheat the oven to 180C/160C Fan/Gas 4.
For the meatballs, melt 50g/1¾oz butter in a frying pan over a medium heat. Add the breadcrumbs and toast until golden-brown, stirring often. If they start to colour too quickly, lower the heat. Set aside to cool.
Mix the mince, salami, egg, fennel seeds and herbs in a bowl. Roll into golf-ball size balls using your hands. Heat a drizzle of olive oil in a frying pan, then add the meatballs and fry them all over to seal. Transfer to an ovenproof dish.
Put the fennel and a tablespoon olive oil in the pan and cook gently for about 10 minutes. Add 2 tablespoons of the onion jam and all of the chicken stock. Bring to the boil, then reduce the heat and simmer until the volume of liquid has reduced by three-quarters. Add the remaining butter and swirl it around so it emulsifies and combines into a sauce. Season with salt and pepper and pour the mixture over the meatballs.
Bake the meatballs for 10 minutes, then remove, sprinkle with Parmesan and spoon over a few tablespoons of ricotta. Return to the oven for 5 minutes, or until the Parmesan has browned. Sprinkle the reserved breadcrumbs and pine nuts evenly over the top and serve immediately.