Begin pastry the day before serving. Into a medium bowl sift flour and salt; add butter or margarine and cream cheese in small pieces. With pastry blender or two knives, scissor fashion, cut butter and cheese into flour mixture until all is well blended. Shape into a ball, wrap in wax paper, plastic wrap or foil, then refrigerate overnight.
Early in the day, or about two hours before serving: Lightly grease two cookie sheets. Heat oven to 400° F.
On floured surface, roll out cheese dough 1/8 inch thick. Then, with 3 x 2 3/4 inch heart shape cookie cutter, cut out hearts. Remove trimmings; re-roll and cut out once or twice again. In center of each of half of pastry hearts, place 1 scant teaspoonful of preserves. Brush their edges with beaten egg, cover each with another cutout heart, then, with fork, lightly press edges together. Arrange on cookie sheet. Brush top of each with beaten egg; sprinkle with granulated sugar, if desired.
Bake 10 to 12 minutes, or until golden; cool on rack.
Servings: about 24