Preheat the oven to 350°F. Line a cookie sheet with parchment paper or a silicone mat and set aside.
In a medium bowl, cream together the butter, Nutella and sugars until light and fluffy. Mix in the egg and vanilla until fully combined.
In a separate bowl, mix together the flour, cornstarch and baking soda. Slowly mix into the wet ingredients, mixing until fully incorporated. Fold in the chocolate chips.
Using a medium cookie scoop (or your hands), form around 15 balls of dough, and place evenly spaced on the prepared cookie sheet.
Bake in the preheated oven for 10-12 minutes, or until edges have set. Depending on how you like your cookies, you can wait for the middle to fully set, or have it almost set for a more soft and chewy cookie.
Allow to cool for 10 minutes on the cookie sheet before transferring to wire racks to cool completely.