Add the hazelnuts to the bowl of a food processor. Process until the hazelnuts form a paste, scraping down the sides if needed. This should take around 3-5 minutes. To the food processor, add all the remaining ingredients. Process until completely smooth, scraping down the sides 2-3 times for about 10 minutes. The Nutella will seem runny, but it will firm up as it cools. Divide the Nutella between your two jars. Decorate the jars as desired. Store at room temperature for 1 week or in the fridge for longer.