At heart this is just a posh version of that simplest of Italian classics, spaghetti oglio, aglio e peperoncino, ie with oil, garlic and chilli. It's so easy as to defy belief. For today's dish, the quality of your ingredients will make all the difference, though I did improvise.
A few pointers. Use your very best quality olive oil. It is the key to the dish. You could get away with using ready cooked prawns, but the flavour will be much better if you cook them in the oil. I normally crush my garlic, but not here. It's essential to slice it. You want it to colour slightly, but watch it like a hawk to make sure it doesn't burn.
The amount of chilli is up to you. To deseed or not to deseed; to go for the burn by garnishing with raw slices. Prawns can compete with a lot of heat: crab less so. If using it, you don't want to overwhelm the delicate taste. Those little tubs of crab meat are a ferocious price, though if you've ever tried to prep one yourself, you'll understand why. I happened to have half a tub of crab pate in my fridge, made up mainly of brown meat. It made a very good addition, whereas white meat might be a bit too delicate.
Parsley? Well, Italian recipes tend to favour the flat leaf stuff. My preference is for curly parsley, but suit yourself. And finally, lemon. Yes, definitely. Plenty of zest, and a good squeeze of juice at the end.
You will have seen many Italian programmes telling you to retain some of the pasta water. You will need that here to loosen your sauce. Simply take a few ladlesful from the pan before you go to drain the spaghetti, otherwise you'll curse yourself as it disappears down the plughole.
All quantities are approximate. Allow 100g of pasta per person (dry weight).
Ingredients (approximate, for about 4 people)
400g spaghetti or linguine; 125ml good olive oil; small handful of raw prawns per person, shelled, and cut to size; I tbsp of brown crab meat per person (or a portion of crab pate) - optional; 1 red chilli, finely chopped, plus more to garnish if desired; 4 garlic cloves, peeled and sliced (not crushed); zest of 1 lemon and fresh lemon juice to squeeze; good handful of finely chopped parsley; large chunk (60 - 80g butter); freshly ground black pepper (not, I'm sure, that you would use any other type).
You can probably make the sauce in the time it takes your pasta to cook. In best Italian mode you will be adding the pasta to the sauce, so make sure your pan is large enough. Warm the oil and gently cook the chilli and garlic until the latter is lightly brown. Add your prawns and cook. When the prawns are done stir in the crab. Add the cooked spaghetti, half of the parsley and the lemon zest. Add some of the reserved cooking water and the butter. Combine well until the butter is melted. Season with pepper, and add more liquid if required.
Serve with a topping of pepper, the remaining parsley, a squeeze of lemon juice and extra chilli if desired.