Add egg whites to a small bowl and let them come to room temperature, at least 30 minutes.
Preheat oven to 250 degrees and line two baking sheets with parchment paper.
Add egg whites, vanilla, cream of tartar, and salt to a mixing bowl. Beat with a whisk attachment until eggs become foamy.
Gradually add the sugar. Once the sugar is incorporated, add a couple drops of red food coloring.
Continue mixing on high until glossy and stiff peaks form.
Add the mixture to a piping bag with a round tip. Pipe heart shapes onto the prepared baking sheets.
Bake the meringue cookies in the oven for 45 minutes. Then, turn off the oven and let the meringues sit in the oven for an hour.
Once the meringues are baked, melt the chocolate over low heat, stirring until chocolate is smooth and melted.
Dip half of each cookie into the melted chocolate. Then, sprinkle with Valentine's Day sprinkles.
Let the chocolate set in the fridge (or at room temperature) and enjoy!
Store the cookies in a sealed bag or container in a cool, dry place.