1: Use soft butter at room temperature.
2: In a bowl, add the butter and sugar and mix until creamy.
3: Add the whole egg and let it absorb into the butter mixture.
4: Gradually incorporate the hazelnut flour and all-purpose flour with a spoon.
5: Transfer the mixture to a work surface and knead with hands until smooth.
6: Take small portions of dough and form balls of similar size.
7: Place the balls on a baking tray lined with parchment paper, slightly spaced.
8: Gently press each ball to flatten a bit and place a whole hazelnut on each.
9: Bake in a preheated ventilated oven at 180°C for about 10-15 minutes.
10: Remove from the oven and let them cool completely before removing from the tray.
