Take the butter out of the fridge 1/2 hour before starting the cake. Cut it into cubes and leave to soften in the open air.
Mix the hazelnut powder, flour, baking powder and vanilla powder in a bowl.
Put the soft butter in a bowl, add the powdered sugar and whisk until the mixture becomes creamy. Then add the eggs, one at a time. Wait until the mixture is smooth before adding another egg.
Add the hazelnut mixture and milk and stir again. The mixture should be fairly compact. Add a bag of hazelnut flakes to the mixture and mix well.
Use the release spray to grease your mold. Pour the mixture into the tin and place in a preheated oven at 160°C. Bake for 1 hour. To check if the cake is cooked through, plunge a knife blade into the heart of the cake, it should come out dry. If not, add another 5 minutes to the baking time.
Turn out while still warm.
For an extra touch of deliciousness, sprinkle your cake with a drizzle of homemade spread and a few hazelnut pieces.