Beat butter and sugar until blended. Add egg yolks, egg white and sour
cream. Beat until smooth. Beat in flour mixture until dough just comes
Form into two disks, wrap in plastic and refrigerate at least 30
Heat oven to 350 degrees F.
Roll out one disk on liberally floured wax paper with a floured rolling
pin to 1/8-inch thickness. Using a 2 1/2-inch star cutter, cut out star
shapes and place on a wax paper-lined baking sheet. Repeat with second disk.
Gather up scraps, form into a disk and refrigerate.
Bake for 10 minutes per batch, until lightly golden.
Slide cookies onto a cooling rack and cool.
Reroll chilled scraps, cut out additional stars and bake.