In the bowl of an electric mixer fitted with the paddle attachment, mix flour, butter, cream, vanilla, and salt until smooth. Flatten dough into 2 equal disks, and wrap in plastic. Chill until firm, 2 to 3 hours.
Arrange rack in middle of oven. Heat oven to 325 degrees F. Line 3 baking sheets with silpat baking mats or parchment paper.
On a well-sugared surface, roll out dough, one half at a time, to a 1/8-inch thickness, continuously sprinkling sugar over the dough while rolling. Using a 2-inch heart-shaped cutter, cut out 72 heart shapes. Place 24 cookies on each baking sheet. Chill all cookies until firm, about 10 minutes.
Bake cookies, 1 sheet at a time, until light golden brown, about 15 minutes. Transfer to a rack to cool.
In a small bowl, stir jelly until smooth. Place jelly in a small pastry bag fitted with a #11 plain round tip, and pipe 1/2 teaspoon per cookie on half of the cookies. Place remaining cookies on top to form sandwiches.
(c)2004 Martha Stewart Living Omnimedia, Inc. All Rights Reserved.