In a large bowl, cream together the butter, Nutella, sugars, egg and vanilla. Set aside.
In a medium bowl, mix together the flour, cornstarch and baking soda.
Slowly mix the dry ingredients into the wet ingredients until fully combined. Fold in the chocolate chips.
Line 2 baking sheets with parchment paper. Form 1 Tablespoon balls of dough, and place them on the baking sheets. Cover and refrigerate for 2 hours.
Preheat the oven to 350°F.
Place the baking sheets in the preheated oven, and bake for 10 minutes, or until the tops are set and start to brown.
Allow to cool on the sheet for 5 minutes, then transfer to wire racks to cool completely.