Mix the hazelnuts, flour, baking powder, sugar and salt in a baking bowl.
In a small pan, melt the butter. Remove from the heat, add the milk and the eggs. Mix everything well, add to the flour mixture form and stir to a thick batter.
Grease a coated pan with a little butter and heat it. Pour in one tablespoon of batter at a time. Bake at low temperature until golden on both sides. Keep warm in the 80 °C hot stove until all pancakes are prepared.
To serve, drizzle with maple syrup.