Beat together butter and cream cheese until light and fluffy. Blend in flour. Chill overnight.
Roll dough about ⅛" thick and cut with 2" round cutter. Spread tops with jam; arrange ½" apart on ungreased baking sheet. (Cookies shrink during baking.)
Bake in moderate oven (350°) 10 to 12 minutes. Remove cookies and cool on racks.