1 c. butter
1/2 c. sugar
2 or 3 egg yolks (hard boiled)
1 tsp. vanilla
2 c. unsifted flour
Jelly

In large bowl, mix butter and sugar at medium speed until light and fluffy. Beat in eggs and vanilla. Gradually add flour until well blended. Refrigerate 1 hour.

Preheat oven to 350 degrees. Work with only 1/4 of dough at a time, keeping remainder in refrigerator. Roll dough into 1 inch balls. Place on ungreased cookie sheet 2 inches apart. Using thumb, make a depression in center of balls. Bake 10 minutes. Remove and make depression again. Fill with 1/4 teaspoon jelly. Bake another 5 minutes. Cool on wire rack.