Preheat your oven to 350°F (175°C). Grease and flour an 8-inch round cake pan.

In a small bowl, combine the ground hazelnuts, flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the wet mixture, alternating with the milk. Start and end with the dry ingredients, mixing until just combined.

Pour the batter into the prepared cake pan and smooth the top with a spatula.

Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.