Combine the butter and confectioner’s sugar in a bowl to form a stiff mixture. Add the flour, nuts, vanilla, cardamom powder and salt, and mix well to form a dough. Let stand for 30 minutes, covered, at room temperature.
Preheat oven to 325°F. Grease a cookie sheet.
Make small balls out of the dough, about 1 inch in diameter, and place them on a cookie sheet. Smash the balls flat with the bottom of a small glass, lightly dipped in flour to prevent sticking, so they resemble irregular clouds. Make sure the cookies don’t touch one another.
Bake for approximately 22 to 25 minutes (depending on the oven). Remove from the oven and dust the tops generously with confectioner’s sugar. Cool on racks.