Peel and clean the prawns. Set the tails aside. In a pan, heat some olive oil over medium heat and add the prawn heads and shells. Cook until they change colour, then press them to release their juices. Remove and discard, keeping the flavoured oil.
Add sliced garlic to the same oil and sauté briefly. Add the prawn tails and cook for about 3 minutes. Then add the sliced cooked octopus and cook for another 2 minutes. Remove everything from the pan, leaving only the oil.
Add the flour to the oil and cook for a few minutes, stirring constantly, so it loses the raw flour taste.
Gradually add the hot milk, little by little, stirring continuously to avoid lumps. Keep cooking until you get a smooth, creamy béchamel.
Season with salt. Finely chop the prawns and octopus, then fold them into the béchamel along with fresh parsley.
Once the mixture thickens and pulls away from the sides of the pan, transfer it to a dish. Cover with cling film directly touching the surface and let it cool. Refrigerate until fully set.
Shape the mixture into croquettes. Coat each one in beaten egg, then breadcrumbs.
Fry in hot oil until golden and crispy. Remove and drain on paper towel.
