This recipe makes 15 x 135g giant cookies (110g cookie dough + 22g Nutella). Mold size for the Nutella inserts: 11.6”x 6.8” x 0.75”, diameter of each cavity is 1.5''/4 cm. Nutella can also be framed using a small tray lined with freezer bag sheet. Once frozen, cut into desired portions. Cookies can be baked with or without tart rings. Tart ring ensures a more evenly distributed cookie dough during baking. For regular size cookies, make 70g dough balls, and insert one half sphere frozen Nutella. Presse down a bit and freeze for 30 minutes before baking. For giant size cookies, use 4.25''/11cm diameter tart rings; grease with butter and flour if using perforated tart ring. For giant XXL cookies, use 6.25''/16cm diameter tart rings. Make 240g cookie dough portions, and split in half. Slightly press down the first half, place in the center 3 frozen Nutella half spheres. Cover with remaining cookie dough; enclose and freeze for 30 minutes before baking. Nutella cookies can be made in advance and kept frozen for up to 3 months. Leave cookies out for 30 minutes, or until dough begins to soften but the Nutella insert.
Toast hazelnuts for about 25 minutes in a 375ºF/190ºC oven. Lower temp to 350ºF/180ºC if using a convection. Note that oven temperature may vary, so keep an eye on the hazelnuts!
In the food processor, turn toasted nuts into paste; add some of the oil to ease processing. For the simple syrup, bring to a boil water and sugar. In a small saucepan, bring to a boil heavy cream, corn syrup and simple syrup. Add chocolates and mix with an immersion blender. Then, add hazelnut butter, and remaining oil – blend well. Fill up half spheres and freeze overnight. Remove frozen Nutella inserts; keep inserts frozen until ready to use.
Sift flour and baking soda together; set aside. In the stand mixer fitted with the paddle attachment, cream softened butter with salt first for a couple of minutes. Add sugars, and mix well until smooth. Do not over mix. Add eggs one at a time; making sure that between each egg, the dough comes out smooth. If it separates, warm up the mixing bowl over the stove for a few seconds, or use a blowtorch. Add sifted powders in 2 times; mixing on low until just combined. Then, add hazelnut meal – Then, crushed hazelnuts and chocolate. Mix on low until complete incorporation. Keep cookie at room temperature until ready to use.
Preheat oven to 375ºF/190. If using convection oven, lower temp to 350ºF/180ºC. Bake cookies for about 22 minutes (Do not over bake). Let cool to room temperature – best within 2 hours. Avoid refrigeration. Enjoy!