Toast the walnuts until golden brown and fragrant, about 5 minutes. Let cool, then chop about half of the nuts.
Pulse the remaining nuts in the food processor until finely ground.
Stir the flour, baking powder, salt and nuts together in a medium bowl. Set aside.
In another medium bowl, beat the butter, sugar, egg yolk, amaretto and almond extract together with an electric mixer on medium-high speed until the mixture gets light and fluffy, about 10 minutes.
At low speed, stir in the nut mixture to make a crumbly dough. Cover the bowl and set dough aside at room temperature for 1 hour.
Preheat oven to 350 degrees F. Line two baking sheets with parchment or coat with nonstick spray.
With a tablespoon, scoop pieces of dough and roll into balls between the palms of your hands. Pinch the ends of the balls to make a football shape. Place the cookies on the prepared baking sheets. Bake until the cookies set and start to brown, about 18 minutes.
Remove cookies from the oven and cool for 5 minutes. Place the warm cookies on a bag with 1 cup of confectioners sugar and shake gently to coat with sugar.
Cool completely and coat in the sugar again. Place the cookies on the rack once more to allow time for the sugar to ader before serving or storing.