Mix the butter, cream cheese, sugar and vanilla together. Beat for about one minute at medium speed. Add the flour and salt. Beat again to mix well. Divide the dough into 4 or 5 pieces. Wrap each piece in waxed paper or plastic wrap and chill in refigerator for 2 to 3 hours. Remove the dough from refrigerator, one piece at a time. Roll a piece of dough on a floured pastry cloth to about 1/8" thick. Cut the dough with a 2" to 2-1/2" round cookie cutter. Arrange the cut-outs, about 1" apart on very lightly greased cookie sheets. Place 1/4 to 1/2 tsp. jam in the center of each one. Fold two edges of the dough to the center to form the shape of a lily flower. Press the edges together slightly to seal the dough on the narrow end. (The cookies should be cone shaped with jam showing on wide end, as shown in the picture.) Bake in a preheated oven at 375º for 8 to 10 minutes or until the cookie edges are a very lightly browned. Cool the baked cookies on wire racks.
To store - After they are completely cool, place the cookies in a can or other tightly covered container. Place the cookies in layers with waxed paper or plastic wrap between each layer to prevent them from sticking together.