Prepare Nutella Balls: Scoop small portions (about 1 teaspoon each) of Nutella onto a parchment-lined tray. Freeze these Nutella portions for at least 30 minutes until they are firm.
Mix Nutella, Egg, and Vanilla. In a large bowl, sugar, egg, and vanilla extract. Mix until smooth and well blended.
Combine Dry Ingredients. In a separate bowl, whisk together the flour, baking powder, and a pinch of salt.
Combine Wet and Dry Mixtures. Gradually add the dry ingredients to the wet mixture, mixing until just combined. Be careful not to overmix.Optional: Add Mix-ins. If you want to add extra texture, fold in chopped nuts, chocolate chips, or hazelnuts into the cookie dough. Preheat Oven: Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
Scoop Cookie Dough. Scoop a tablespoon of cookie dough and flatten it in your palm. Place a frozen Nutella ball in the center and wrap the dough around it, forming a ball. You may need to add more cookie dough to cover the top. Make sure the dough is completely sealed around the Nutella.
Place on Baking Sheet. Arrange the Nutella-stuffed cookie dough balls on the prepared baking sheets, leaving space between each.Flatten Cookies (Optional). You can flatten the cookies slightly with the back of a spoon or fork for a classic cookie shape Bake. Bake in the preheated oven for 8-10 minutes or until the edges are set. The centers may still be soft but will firm up as they cool.
Cool. Allow the Nutella-stuffed cookies to cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely. Enjoy!