Preheat oven to 400°. Unfold piecrusts on a lightly floured surface and roll to press out fold lines. Cut with a 2-inch, heartshaped cookie cutter. Reroll remaining dough and repeat procedure. (There should be a total of 46 pastry hearts.) Brush one side of each pastry heart with egg white and sprinkle evenly with granulated sugar. Place pastry hearts on two ungreased baking sheets.
Bake for 7 to 8 minutes or until lightly browned. Remove cookies to wire racks and let cool. Stir together cream cheese, powdered sugar, 2 Tbsp. butter and almond extract until blended.
Spread cream-cheese mixture evenly over unsugared side of half of the heart cookies, followed by about 1/2 tsp. preserves. Top with remaining hearts, unsugared sides down.
Microwave white chocolate morsels and 1 Tbsp. butter in a glass bowl on high for 1 minute or until melted. Stir mixture until smooth; seal in a small, heavy-duty zip-top bag. Snip a tiny hole in one corner, then drizzle mixture over tarts. Cool completely; sprinkle with red sugar and place in candy boxes, if desired.