Preheat the oven to 350°F and grease a 9×13″ pan.
In a large bowl, cream the butter, both the sugars and vanilla essence
Add eggs one at a time.
Heat the Nutella jar in the micro for about 20-30 seconds, just till it has a runny consistinecy and you can pour it easily.
Remove from oven and let cool for 10-15 minutes.