Meanwhile, make the dressing. Using a hand mixer or a food processor, add the fresh basil leaves, walnuts, cream, mayonnaise, parmesan, olive oil, garlic clove, salt, and ground pepper to the bowl and blitz until everything is combined and the dressing is creamy.
⅓ cup fresh basil leaves, ¼ cup heavy cream, ½ cup mayonnaise, 1 garlic cloves, ¼ cup finely grated parmesan cheese, ½ cup walnuts, ½ teaspoon salt, 3 tablespoons olive oil, ¼ teaspoon ground pepper