Preheat your oven to 350°F (175°C). Adjust oven racks to the middle position and line a baking sheet with parchment paper.

In a large mixing bowl, cream together the softened unsalted butter, granulated sugar, and brown sugar until light and fluffy, about 3 to 5 minutes.

Add the eggs one at a time and mix well after each. Stir in the vanilla extract until combined.

In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add to the wet mixture, mixing on low until just combined.

Fold in the chopped hazelnuts, chocolate chips, and crushed cornflakes until evenly mixed.

Drop rounded amounts of dough onto the baking sheet, spaced about 2 inches apart. Bake for 10 to 12 minutes until golden at the edges.

Let the cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.