Preheat the oven to 350ºF. Line a baking sheet with parchment paper or silicone mat.
Combine the flour, cocoa powder, baking soda, cornstarch, and salt in a medium bowl. Stir with a whisk to combine.
In the bowl of a stand mixer fitted with the paddle attachment or with a hand held electric mixer, beat the butter and sugars until fluffy. Beat in the eggs one at a time, mixing well after each addition. Beat in the vanilla and Nutella. Slowly add the flour mixture and mix just until combined. Fold in the chocolate chips.
Drop 1 tablespoon size balls of dough about 2-inches apart onto the prepared baking sheet. Bake for 10 to 12 minutes or until edges look dry. Cool on the pan for 5 minutes before transferring to a wire rack to cool completely.