In a heatproof glass bowl, add the sugar, egg whites, and cream of tartar. Place the bowl on top of a larger pot with about 2 inches of simmering water.
Whisk the mixture constantly until the sugar has dissolved or reached 160 degrees, about 5 minutes. The mixture will become frothy.
Add the frothy egg mixture into a stand mixer bowl and add the vanilla extract. Mix on high for 5 minutes. Put the meringue into a piping bag fitted with a star tip.