As soon as you buy the 450 grams Manilla clams, put them in a large container and fill with salt water (it should taste like the sea). Over the next day or two watch the water as the clams spit out sand. If you see a lot of sand accumulating on the bottom, rinse the clams and change the water.
When you're ready to make the pasta, boil the 180 grams spaghetti for one minute less than the time specified on the package in lightly salted water. This is because it will finish cooking in the sauce
When the pasta is about 3 minutes away from being done, add the 2 tablespoons extra virgin olive oil, 10 grams garlic and 1 chili pepper to a large pan over medium heat until the garlic starts to sizzle and becomes fragrant.
Add the clams and 3 tablespoons dry white wine and then cover the pan with a lid. Let the clams steam until half of them are open.
Remove the lid and turn up the heat to high and boil the mixture until the rest of the clams open. If some clams don't open, discard the ones that don't open.
Drain the pasta and add it to the clams along with the 7 grams flat-leaf parsley. Toss to coat and serve immediately.