Preheat oven to 200 degrees and line two baking sheets with parchment paper.
Combine egg whites and cream of tartar in the bowl of a stand mixer.
Beat at medium-low speed until eggs are frothy, about 2 minutes
Gradually beat in sugar. Continue to beat until stiff peaks form, about 15 minutes.
If you like, swirl a few drops of food coloring.
Transfer to a piping bag fitted with a plain round piping tip.
To make the hearts, pipe two small upside-down teardrop shapes with the sides touching. Repeat with the remaining meringue.
Bake for 1 hour, until the meringue is dry, can be lifted easily from the parchment, but not yet browned. Then turn off the oven. Leave meringue in the oven to dry out until the oven is cool.