Line a baking sheet with a silicone mat. Set aside. In
the bowl of a stand mixer fitted with the paddle attachment whisk
together the egg and 3/4 cup Nutella for about 2 minutes until the
mixture is glossy.mAdd flour and beat until combined.
bowl with plastic wrap and let rest in the fridge for 10-15 minutes.
Don’t leave the dough longer in the fridge or the dough will get cracked
when forming the balls.
Preheat the oven to 350°F (177°C).
Using a tablespoon, scoop out dough and form 20-25 cookie balls. Place cookie balls on the baking sheet. Use your finger or the end of a wooden cooking spoon to make a well in the center of each cookie. Fill the hole with some chopped nuts. Sprinkle chopped hazelnuts on top of the Nutella. Bake for about 10 minutes. Take the cookies out of the oven and let them cool down a bit to firm up.