In a food processor, blend the basil, oil, nutritional yeast, lemon juice, miso paste, salt, garlic, and walnuts together until smooth. Set aside.
Spiralize the squash using Blade C. Once the squash has been spiralized, I like to give all the noodles several rough chops so that they're easy to eat (otherwise, the noodles are too long). Chop up the parts of the squash that did not get spiralized and add them to the salad. If you do not have a spiralizer, create vegetable noodles with a julienne peeler or vegetable ribbons with a regular peeler.
In a large bowl, toss the noodles, diced peaches, cherry tomatoes, and 1/3 to 1/2 cup of the pesto sauce together.
Store the unused pesto and leftover salad in separate containers and refrigerate.