Cream the butter and sugar until well blended in a largebowl.
Beat in the eggs and vanilla. Work in the flour until afirm dough forms.
If the dough seems too sticky, let it chill for a coupleof hours in the refrigerator.
Form the dough into 1-inch balls and place 2 inches aparton ungreased baking sheets.
Use a clean thimble to press a hole in each one.
Bake until the edges of the cookies are golden brown and the jam begins to bubble, about 25 minutes.
These cookies will stay fresh for up to 5 days.