Cream butter; gradually add 2/3 cup sugar, beating at medium speed of an electric mixer until light and fluffy.
Add egg yolks, one at a time, beating well.
Combine flour and salt; add to creamed mixture, beating well.
Shape dough into a ball; cover and chill at least 2 hours.
Divide dough in half; store 1 portion in refrigerator.
Sift powdered sugar lightly over work surface.
Roll half of dough to 1/8 inch thickness; cut with a 2 1/2 inch round cutter.
Roll remaining dough as before; cut with a 2 1/2 inch doughnut cutter, reserving centers.
Chill dough, if necessary.
Combine 1/2 cup sugar and almonds; mix well.
Beat egg whites until frothy.
Brush one side of all cookie cutouts with egg white, and coat with almond mixture; place coated side up on lightly greased cookie sheets.
Bake at 375° for 8 to 10 minutes or until lightly browned.
Cool on wire racks.
Repeat procedure with remaining dough.