Preheat overn to 350.

Thoroughly mix sugar and butter

Add egg yolks and vanilla, continue to mix.

Add flour in small amounts and mix thoroughly.

Roll dough into balls the size of a quarter.

Press thumb into center of each ball and fill with jam.

Bake 10-12 minutes or until edges of cookie turn light brown.

These are always a big hit at parties.  Delicious!

Send me PM if you have any questions.