In a large bowl, beat margarine, sugar, vanilla and salt on medium-low until combined. Slowly beat in whipping cream. Gradually beat in enough flour until dough is no longer sticky. Divide dough into four portions, then flatten into disks. Wrap in plastic; refrigerate at least 2 hours or overnight., Preheat oven to 350°. On a lightly floured surface, roll each portion of dough into a 12-in. circle; spread each with 1/4 cup raspberry jam. Cut each circle into 16 wedges., Gently roll up wedges from the wide ends. Place 2 in. apart on parchment-lined baking sheets, point side down. Bake 25-30 minutes or until light golden. Remove to wire racks to cool., If desired, combine confectioners' sugar and milk until smooth. Drizzle over cooled rugelach.