Scoop tablespoon size of the Nutella hazelnut chocolate spread and freeze them until needed.*To make scooping easier, I recommend pre-freezing the Nutella until semi-solid to scoop and portion into tablespoon size balls.*
Preheat oven to 350°F and prepare sheet pans lined with parchment paper.
Combine the 3 Tablespoon of sugar and 2 teaspoon of ground cinnamon and mix until well distributed. Set aside until needed.
Whisk together the flour, baking powder, and salt. Set aside.
In a large mixing bowl, combine the softened unsalted butter and ¾ cups of granulated sugar and beat until light and fluffy. Add the egg and vanilla and mix until well combined. Add the flour and mix by hand or on low speed just until the flour is incorporated.*DO NOT overmix or it will result in tough cookies!*
Divide the dough into 9 two inch balls, about 2 full but flat scoops of standard 1½ inch cookie scoops. Make a deep indentation in the cookie dough and stuff it with the pre-portioned frozen Nutella balls. Pinch together the opening and roll the cookie dough into a smooth ball to seal the Nutella filling. Repeat with remaining cookie doughs.*Make sure to work fast because Nutella melts pretty fast and will get messy.*
Once all the cookie doughs have have been stuffed with Nutella, roll each cookie dough in the cinnamon sugar mix and sprinkle the cinnamon sugar on each dough ball. Place all cookie doughs onto the prepared sheet pans about 2 inches apart.*Optional: to make the cookies extra flat, you can gently flatten the cookies to about 1 inch thick, but it's really not necessary.*
Bake the cookies for about 10-12 minutes, or until the edge of the cookies set slightly and the middle of each cookie has puffed up for about 1-2 minutes. Remove the cookies from the oven and sprinkle the remaining cinnamon sugar evenly amongst the cookies.
Let the cookies cool for a few minutes and enjoy!
These cookies are good for up to 4 days at room temperature if properly stored in an airtight container.
You can also make the cookies ahead of time, freeze the dough after stuffing it with Nutella, and simply let it thaw and come to room temperature before baking. If baking the cookies while they are cold, make sure to adjust the baking time accordingly.
If you wish to multiply this recipe, make sure to add the eggs 1 at a time and beat until incorporated after each addition.