Bring 5 quarts of water to a vigorous boil and add salt to taste. Add 1 lb of spaghetti. Stir well until water returns to the boil. Cook 2 minutes.

Remove the pot from the heat and cover first with a clean cloth, then with a lid. Let stand 9 minutes without uncovering the pot. Drain and toss with 1 tbsp butter or olive oil. Serve with a sauce.