In a clean, dry mixing bowl, beat egg whites and cream of tartar until soft peaks form.

Combine sugar, corn syrup, and water in a saucepan. Cook over medium heat, stirring occasionally, until the sugar dissolves and the mixture reaches 240°F on a candy thermometer.

With the mixer running on low, carefully pour the hot syrup into the egg whites in a slow, steady stream.

Increase the mixer speed to high and continue beating until the mixture is thick and glossy, about 7-8 minutes.

Add vanilla extract and beat until incorporated.

Use immediately or store in an airtight container at room temperature for up to two weeks.