Short answer: it depends on your strictness and guidance from your guru.

In Digambar Jain practice during Paryushan, many followers undertake very strict ahimsa-based vrata, which often means:

• No root vegetables or foods that involve harm to living beings, and
• If you personally avoid dairy or animal-derived products, then dairy-containing foods are not allowed.

Nutella ingredients include skim milk powder (a dairy product) and palm oil. If you follow a stricter Digambar discipline that avoids dairy during Paryushan, Nutella would not be allowed. If your local guru or community approves dairy for you during your vrata, some might permit it.

Because rulings can vary by sangh and guru, please check with your own guru or the specific guidelines your community follows for Paryushan.