Start by cleaning the prawns. Remove the heads and set them aside. Shell the tails and keep the shells. Place the heads, shells and 12g of salt in a pot, with 2 litres of water. Bring to boil and then reduce the heat and simmer for 20 minutes. Then pass the cooking liquid through a sieve, discard the shells and heads and keep the resulting fish stock warm over a low heat.
Melt 10g of butter in a large heavy-bottomed saucepan, stir in the rice and sauté, stirring for about 3 minutes, until the grains are coated in butter. Then cover the rice with a couple of ladlefuls of the fish stock and cook, stirring, until all the liquid has been absorbed. Then add some more stock, a ladleful at a time, allowing it to be absorbed by the rice before adding the next ladleful. It will take about 20 minutes for the rice to cook. After 15 minutes, add the prawns to the dish.
In a separate small pot boil the petit pois for 5 minutes in a little salted water. Once cooked, drain the peas and blend them with some olive oil to form a bright, smooth cream. Put it through a sieve if necssary.
Cut the small squid into thin strips and pan-fry for 5 minutes with a drop of olive oil and a pinch of salt. These will be used for presentation.
When the rice is cooked and the mixture is not too runny, remove the pan from the heat, add in the remaining butter and the cuttlefish ink and stir until the rice is nicely black and creamy.
To serve, spoon a little of the pea cream into the centre of a large soup plate and using a ring mould place the risotto in the centre of the plate. Place the fried squid over the risotto. Remove the ring mould carefully and serve hot.