Recipe courtesy of Burgi Riegler, Pastry Chef, Konditor.Yield is 50 cookies.
Preheat oven to 350 degrees F.
Line a baking sheet with parchment paper.
In a stand mixer with the paddle attachment, mix the butter, sugar, vanilla and salt until creamy.
Add the egg and continue mixing until combined.
Combine flour and ground walnuts in a separate bowl and then add them to the butter mixture.
Stir to combine.
Put the mixture in a piping bag fitted with a round tip and pipe 3-inch-long half moons on the parchment-lined baking sheet about 1 inch apart.
Sprinkle with sugar while cookies are still hot from the oven.