In a bowl, with an electric mixer on medium speed, or in a food processor, beat or whirl butter, 1 1/2 tablespoons powdered sugar, and the egg yolk and flour until smooth and well blended. Stir in almonds.
Shape dough into 1 1/4-inch balls and, using your fingers, roll each into a 2-inch rope. Set ropes on buttered or cooking parchment-lined 12- by 15-inch baking sheets. With your fingers, pinch ends in opposite directions to make S shapes.
Bake cookies in a 300° oven until pale golden, 20 to 25 minutes; if baking more than one pan at a time, switch pan positions halfway through baking. Let cool on sheets for 5 minutes.
Place remaining 1 1/3 cups powdered sugar in a shallow bowl. Gently turn warm cookies in sugar, a few at a time, then set on racks to cool. When cool, coat cookies again with powdered sugar.