Preheat oven to 325 degrees.
Whip butter. Add sugar, 6 egg yolks, and flour.
Mix well. Roll dough into 1-inch balls.
Roll in egg whites and then in crushed flakes.
Place on greased cookie sheets and press down with your thumb.
Bake for 5 minutes.
Then repress and continue baking 5-10 minutes longer.
Remove from oven and let cool.
Fill centers of cookies with jam.