Fill a 4-quart Dutch oven about half full of water. Add 1/2 teaspoon salt if desired. Cover with lid; heat over high heat until the water is boiling rapidly. Add the pasta. Heat to boiling again. Boil uncovered 14 to 16 minutes, stirring frequently, until tender but not mushy. While the water is heating and the pasta is cooking, continue with the recipe to make the pesto.
To measure basil, firmly pack basil leaves into a measuring cup. Use a measuring cup for measuring dry ingredients. Rinse the basil leaves with cool water, and pat dry thoroughly with a paper towel or clean, dry kitchen towel. Peel the garlic cloves.
In a food processor or blender, place the basil leaves, garlic, cheese, oil and pine nuts. Cover and process, stopping occasionally to scrape sides with rubber spatula, until smooth.
Place a strainer or colander in the sink. Pour the pasta in the strainer to drain, and place in a large serving bowl or back in the Dutch oven. Immediately pour the pesto over the hot pasta, and toss until pasta is well coated. Serve with additional grated Parmesan cheese if desired.