Rinse and scrub the clams very well to remove any surface dirt. Add them to a large bowl, cover with cold water and add 2 teaspoons kosher salt. Stir to agitate, add 1 cup of ice and let stand 20 minutes for the clams to filter any sand in their shells. Drain the water, rinse the clams once more, and set aside. Discard any clams that do not close when gently squeezed or have broken shells.

Bring a large pot of water to a boil. Season with 1 tablespoon kosher salt, add the pasta and cook until slightly firm, around 10 minutes.

In a separate sauté pan, add 3 tablespoons olive oil, garlic and chile, if using. Place over medium heat and gently cook, stirring, until golden, around 2 minutes. Add the clams, half of the parsley and toss to coat. Add the white wine and cover with a lid. Cook until the clams have opened, around 6 minutes. Using a slotted spoon, transfer the cooked clams to a bowl and set aside. If any clams are still closed, continue cooking, covered with a lid, until they have opened. Discard any that remain closed.

Add ½ cup of the pasta cooking water to the sauce along with the drained spaghetti, 1 tablespoon olive oil, and the remaining parsley. Toss to coat and cook, stirring, until the pasta is cooked to your preferred doneness, around 2 minutes for al dente. Taste for seasoning and adjust with salt as desired. Transfer to serving bowls, top with the reserved clams, finish with a drizzle of olive oil and serve immediately.