Boil water to cook the pasta. In a food processor or blender, process the basil, parsley, and garlic until finely chopped. Add the anchovies, oil, lemon juice, and pepper. Puree to a smooth paste. Carefully flake the tuna into a large bowl and gently fold in the mixture. Cook the spaghetti until al dente. Drain and rinse, return to pan and add 3 tablespoons of olive oil. Over a moderate flame, heat the spaghetti, tossing with oil until hot. Add the tuna mixture and toss lightly. Serve immediately. Add Parmesan cheese if desired. Makes 6 servings