Add the butter, sugars, Nutella, egg and vanilla extract to the bowl of a stand mixer and mix with the paddle attachment until combined and creamy.

In another medium bowl, add the flour, cornstarch, baking powder, baking soda and salt and mix with a whisk.

Add one cup of the dry mixture to the wet and mix until just combined - then repeat with the remaining flour.

Fold in the chocolate chips.

Cover the bowl with plastic wrap and refrigerate for 3 hours or more.

Preheat oven to 375°F.

Line a cookie sheet with parchment paper then using a cookie scoop take 2 Tablespoons (or 2 scoops) of the cookie dough and quickly roll a little with your hands.

Lay on the cookie sheet, 2 inches apart. 

Bake for 10-12 minutes. Remove from the oven and allow to set up some more on the cookie sheet, for about 10 minutes before moving to a wire rack to cool completely.