Toast the almonds and hazelnuts in a dry pan over medium heat until golden brown. Immediately remove from the pan and allow to cool slightly.
Place the parsley (leave a little aside for garnish) in a food processor with the nuts and process on high, add 2 tbsps olive oil and process on high until smooth.
Stir this into the tomato sauce together with the fish stock, bring it all to the boil and reduce to simmer.
Add some salt and pepper to some flour and lightly coat the squid pieces. Fry them on high in a large deep pan in a liberal amount of oil for a couple of minutes.
Repeat the same process for the perch.
Clean the pan, return to the heat with some more oil, and fry the prawns on high for a minute or two.
Add the mussels, squid, clams, and a little of the clam brine and pour in the simmering sauce. Reduce the heat to medium and add the scallops and perch.
Once the mussels have all opened, all the other seafood should be perfectly cooked. Season to taste.
Depending on the occasion, you may want to just place the pan on the table with a chopping board of bread, or you may want to plate it up. If so, arrange your 4 plates and divide the seafood evenly among them using a set of tongs, and then ladle the sauce over. Sprinkle over some parsley and serve with a red or white wine.