In a blender container or food processor bowl combine the 3/4 cup chopped zucchini, mayonnaise or salad dressing, sour cream, buttermilk, basil, garlic powder, onion powder, and pepper. Cover and blend or process until mixture is almost smooth. Stir in the 1/4 cup finely chopped zucchini, if desired. Cover and store in the refrigerator for up to 1 week. Makes about 1 cup (sixteen 1-tablespoon servings).