Prepare the Meringue:

1. Preheat the Oven: Preheat your oven to 200°F (93°C) and line a baking sheet with parchment paper.
2. Whip the Egg Whites: In a clean, dry mixing bowl, beat the egg whites using an electric mixer on medium speed until frothy.
3. Add Cream of Tartar: Add the cream of tartar and continue beating until soft peaks form.
4. Add Sugar Gradually: Slowly add the granulated sugar, about 1 tablespoon at a time, while beating on high speed. Continue beating until stiff peaks form and the meringue is glossy and holds its shape.
5. Add Vanilla Extract: Mix in the vanilla extract.
6. Add Food Coloring (Optional): If desired, add a few drops of food coloring to the meringue and gently swirl it in for a marbled effect.

Shape the Meringue Kisses:

7. Prepare a Piping Bag: Transfer the meringue into a piping bag fitted with a star tip (or a zip-top bag with the tip of the corner cut off).
8. Pipe the Meringue: On the prepared baking sheet, pipe small kisses by creating a small peak and then lifting the piping bag to form the signature meringue kiss shape.
9. Bake the Meringue Kisses: Bake in the preheated oven for 1 hour, or until the meringue kisses are crisp and easily lift off the parchment paper. They should not brown.
10. Cool the Meringue Kisses: Turn off the oven and allow the meringue kisses to cool completely in the oven with the door slightly ajar for 30 minutes. This helps them set and avoid cracking.

Garnish and Serve:

11. Add Garnishes (Optional): Once the meringue kisses are completely cool, you can sprinkle them with edible glitter or heart-shaped sprinkles for a festive touch.
12. Serve and Enjoy: Arrange the meringue kisses on a serving plate or in a gift box for your Valentine’s Day celebration.