Let egg whites stand, covered, in a large stainless-steel or glass mixing bowl at room temperature for 30 minutes. Meanwhile cover two large baking sheets with parchment paper.

Preheat oven to 300 degrees F. In a small mixing bowl stir together seedless raspberry jam (at room temperature) and red food coloring. Set aside.

In a small bowl, combine the superfine sugar and powdered sugar; set aside. Uncover eggs and add cream of tartar. Beat with an electric mixer on medium speed until soft peaks form (tips curl). Add sugar mixture, 1 tablespoon at a time, beating for 5 to 7 minutes on medium speed or until stiff glossy peaks form (tips stand straight up) and sugar is dissolved.

Use a spatula to gently fold 1/2 cup of the meringue mixture into the jam; then gently fold jam mixture into the remaining meringue.

Using a pastry bag fitted with a large star tip, pipe the meringue in 2-inch freeform hearts or Xs and Os onto the parchment paper.

Place baking sheets in preheated oven. Turn off oven. Let meringues dry in oven, with door closed, for 1 hour or until dry and crisp but still light in color. Let cool on parchment paper. Gently remove meringues. Put one or two meringue cookies into a paper bake cup. Carefully tuck one end of each valentine message into each cup.