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

In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy (about 2-3 minutes).

Add the egg and vanilla extract to the butter mixture, mixing until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Fold in the chopped hazelnuts until evenly distributed throughout the dough.

Using a tablespoon, scoop out portions of dough and roll them into balls. Place them on the prepared baking sheet, spacing them about 2 inches apart.

Using your thumb or the back of a spoon, make an indentation in the center of each cookie ball.

Fill each indentation with about 1 teaspoon of chocolate hazelnut spread.

Bake in the preheated oven for 10-12 minutes, or until the edges are set. Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.