Cream sugar and butter in an electric mixer until light and fluffy.
Blend in flour and vanilla just until combined.
Cover and chill for 1 hour.
Preheat the oven to 350°.
Roll chilled dough into balls the size of a walnut and place on an ungreased cookie sheet.
Use the back of a ¼ teaspoon and make a dent in the center of each ball. Fill with ¼ teaspoon of jam.
Bake at 350° for 12 minutes. Let cool on cookie sheet for 5 minutes then move to a wire rack to cool completely.