In a medium size mixing bowl, whisk together flour and salt.
Add cubed butter. Cut into the flour mixture. using a pastry blender or two forks until it resembles small pea size pieces.
Gradually add ½ cup cold water, mixing well. Add additional water one tablespoon at a time until the dough comes together.
Once the dough has come together pat into an even thickness round disk. Cut into 4 sections. Wrap each with plastic wrap and chill for 30 minutes.
Once chilled, working with one dough section at a time, on a lightly floured surface, roll approximately ⅛” thick. (Make small red hearts first.)
To make hearts: With a small knife or cookie cutter, cut out ½ heart shapes working along the edge of the dough. In a small bowl mix together one egg white with 1 tablespoon sugar and the red food coloring until fully blended. Using a small pastry brush, apply red colored egg white over the tiny hearts. Set aside and allow to dry while you assemble pies.
In a separate bowl mix the remaining 2 egg whites with 3 tablespoon sugar. (Use this to brush dough for cherry pies)
To bake: Preheat oven to 350°F. Line 2 large cookie sheets with parchment paper. Set aside.
To assemble: Using a heart shaped pie press, or a 3 inch heart shaped cookie cutter, cut out large hearts. Brush hearts with egg white-sugar mixture.
Dollop 1 tablespoon cherry pie filling onto the center of half of the cutout hearts, leaving a border around the edge. If using a pie press, place another heart on the opposite side and close to seal. If using a cookie cutter, place another pastry heart on top of the pie filling, and press the edges using the tines of a fork or pastry wheel. Arrange on parchment lined sheet pans.
Affix red hearts onto the tops using egg white-sugar mixture. Sprinkle tops with additional sugar.
Place into the preheated oven and bake for 25-30 minutes or just until lightly golden.
Cool for 1 hour on a cooling rack. Serve at room temperature, warm or chilled.
Store in an airtight container chilled for up to 3 days.