1 and ¾ sticks unsalted butter, at room temperature
2 large eggs, at room temperature
2 tsp vanilla extract
1 tbsp sea salt
Using a 1 teaspoon measure, scoop out Nutella and place in small heaps on a cookie sheet lined with parchment paper. Place in the freezer for 15 minutes. (I found using two small trays of plates work best because you can rotate them between the freezer and the kitchen counter as you are preparing each batch of cookies.)
Preheat the oven to 350 degrees F. Line 2 large baking sheets with parchment paper.
In a medium bowl, whisk together flour, baking powder, and salt. In a large bowl, beat butter and 1½ cups granulated sugar with an electric mixer set on medium speed until the mixture is creamy and fluffy. Beat in the eggs and the vanilla extract.
Set the mixer to low speed and gradually add in the flour mixture until it is just combined.
Place ¼ cup granulated sugar in a small bowl. Use 1 heaping tablespoon cookie dough for each cookie. Split the piece of dough in half and slightly flatten the each half with the palm of your hand. Sprinkle a pinch sea salt on one half of the flattened dough.
Remove the frozen Nutella from the freezer and use a small metal spatula to lift the frozen Nutella from the parchment paper. Lay it on the bottom half of cookie dough, on top of the sea salt. If the Nutella starts to soften, place back in the freezer for a few minutes (or alternate with the other tray if you do two trays in the first step.)
Cover the bottom half and frozen Nutella with the other piece of cookie dough. Gently seal the edges with your fingers. Roll the cookie in the sugar to lightly coat it and place it on the prepared baking sheet.
Repeat with the remaining dough and frozen Nutella, spacing the cookies about 2 inches apart from each other on the baking sheets. I found it easiest to prep about 6 cookies at a time in an assembly line fashion.
Bake the cookies, one sheet a time. They are done when the edges are set and beginning to brown, 10 to 13 minutes. The centers of the cookies should still be soft and puffy.
Remove the cookies from the oven and allow to cool on the baking sheet for 10 minutes. Transfer cookies to cool on a rack. Enjoy warm or at room temperature!
Recipe by 2 Sisters 2 Cities at http://www.2sisters2cities.com/2012/12/four-nutella-and-sea-salt-stuffed-sugar-cookies/