Preheat oven to 375°F. Measure flour and salt into a bowl. Using a pastry blender, cut the butter and cream cheese into the flour mixture until well blended. Gently shape the dough into a ball and wrap in clear plastic. Refrigerate for at least 2 hours or overnight. Lightly grease 2 cookie sheets. On a floured surface, roll the dough 1/8" thick. With a heart-shaped cookie cutter, cut out the hearts. Place a teaspoon of the apricot preserves in the centers of half the hearts. Place a heart on top of each apricot filled heart. Lightly press the edges of the hearts together with a fork, sealing well. Arrange the hearts on cookie sheets and brush the tops of each with the beaten egg. Sprinkle with sugar. Bake 10 to 12 minutes or until golden. Cool on rack. Makes 24 hearts using a 3-1/4" x 2-1/2" heart.