1. Pick over several bunches of basil, selecting only unblemished leaves. Pull them from the stems, then rinse under cool running water to wash off any sand or dirt. You will need a total of 8 cups of basil leaves, loosely packed.
2. To enhance their sweet nutty taste, toast pine nuts (pignoli) in a dry nonstick skillet until just beginning to brown, shaking skillet as they cook, taking care not to burn. You will need a total of 2 tablespoons. Toasted walnuts may be substituted.
3. Whirl basil and 1 clove garlic in food processor or blender (you may have to do this in batches) until smooth. Add pine nuts, 3 tablespoons chicken broth, 2 tablespoons grated Parmesan, 3/4 teaspoon salt and 1/4 teaspoon black pepper.
4. Process ingredients until smooth. With processor running, add 3 tablespoons olive oil in a steady stream. Use immediately, refrigerate for several days or freeze for 2 to 3 months. Makes 1 cup.