Beat butter at medium speed until light and fluffy (by hand it takes 20-30 minutes). Add confectioners sugar, yolk, vanilla, orange juice, and brandy or ouzo and mix well.
Sift together the baking powder, cornstarch, and flour. Add slowly to the butter mixture. Dough should be a little sticky. Add more flour as needed, but a little at a time.
Add ground almonds and mix well. Chill dough for at least 15 minutes so it is easier to roll.
Pinch off a walnut-sized portion and shape into small balls or crescent shapes. Place onto ungreased cookie sheet and press down slightly.
Bake at 350˚F for 15-20 minutes. Cookies are done when toothpick placed into center comes out clean. Be careful not to overcook!
Sift confectioners sugar onto another cool baking pan. Put warm cookies on the pan, then sift more sugar on top. Let cool, then cover pan or transfer to a plastic storage container. Use wax paper to separate layers.
To serve, place cookies on serving plate, then dust with a bit more sugar. Optionally, you may place each cookie into a baking cup.