Wash the celery and blend both the stalks and leaves with the toasted hazelnuts, cheese, salt, and a drizzle of extra virgin olive oil until smooth. Add a little cold water as needed to achieve a creamy consistency while keeping the pesto bright green.
Cook the pasta in salted boiling water. Finely chop the Mioorto chives. Drain the pasta, reserving a little of the cooking water, then toss it with the celery pesto, adding some of the reserved water if needed to loosen the sauce.
Serve topped with the chopped chives and a sprinkle of crushed toasted hazelnuts.