Preheat the oven to 180 º C.
In a food processor, blitz the hazelnuts to a powder.
Mix hazelnut, flour, baking soda, baking powder, salt and cocoa powder in a bowl. Set aside.
In another bowl, beat the eggs with sugar, butter and vanilla.
Heat up the milk in the microwave or stovetop, stopping before it boils.
Add the instant chocolate and mix.
Pour the hot chocolate into the wet ingredients and stir.
Slowly add the dry ingredients until they are fully incorporated.
Spread this mixture in a bundt pan (mine is about 24 cm in diameter), previously greased and dusted with flour.
Bake for about 40 to 50 minutes, or until a skewer insert in the cake comes out dry.
Let it cool down for 10 minutes. Remove the cake pan and let it cool down fully. Dust with powdered sugar to your liking.