For 4 people:
Wash the clams very well and discard any that are already opened.
I picked up a very good tip a few years ago on how to clean the clams.
If the time allows, put them into a bowl with salted cold water and leave in the fridge until you need them (changing the water every couple of hours).
In a large pan bring water with some salt to the boil. Add the pasta and cook for 1-2 minutes less than recommended on the packaging ( that way you will get the pasta al dente, with some bite to it rather then overcooked). Before the end of cooking reserve some of the cooking water on the side.
In the meantime, in a separate pan heat up a couple of tablespoons of olive oil and gently fry squashed garlic with the red chilli pepper. Remove and discard the chilli after frying.
I like to open the clams separately and in order to do that put a big empty pot on the heat. Once you can feel the heat coming through the pot, now is the time to add the clams. Put a lid on for couple of seconds, shake the pan. Now add the wine and put the lid back on. Cook for several minutes shaking the pan periodically. After a couple of minutes check if the clams have started to open. If they are not ready, put the lid back on and wait few more minutes.
Drain the clams reserving the cooking juices. I find very often that the clams are salty enough and don’t need any extra salt added to the dish.
When the pasta is ready add it to the pan with the oil (warm) , stir very well, add some clam cooking juices and carry on cooking. If the spaghetti is too dry ( there is no sauce) add some reserved cooking water and more clam juices.
Add the clams ( you can peel take some out the shell beforehand and leave some with the shell still intact if you don’t want too many shells in the dish).
Give it a stir, add the chopped parsley. Adjust the seasoning with black pepper if needed.
Serve while still warm.