I don't recognize this as any specific recipe but if the sauce is as "loose" as your description it probably really is a zuppa or minestra. Just winging it but, peel and devein the shrimpsters, setting the shells aside. You can make a quick stock from the shells with just water and a bay leaf and maybe flat leaf parsely or bouquet garnie. What you will want to do is to cook the pasta in the soup. So, in a deep pot saute your aromatics---chopped onion or shallot, and garlic---in olive oil. Off heat (to avoid splatter, strain in your shrimp stock, along with some tomatoes either pureed or squeezed with your hands. Sea salt and pepper). Return to heat and bring to a fairly fast simmer. Add the pasta (orzo or other small form such as riso) and cook to al dente. I wouldn't add the shrimp until close to the end because they will cook fairly quickly depending on their size. You could probably add mussels or clams to this if you steam them open. For another herb, a chiffonade of fresh basil would work. I'm not sure if this matches your friend's recipe, I'm just trying to think like a Neapolitan dock worker here.