Swiss Meringue

Fill a medium saucepan one quarter full with water. Set over medium heat, and bring water to a simmer.

Combine the egg whites, sugar, and cream of tartar in the bowl of an electric mixer, and place over saucepan. Whisk constantly until sugar is dissolved and whites are warm to the touch, about 3 minutes. Rub the mixture between your fingers to test.

Transfer bowl to mixer stand, and whip, starting on low speed and gradually increasing to high, until meringue is cool and stiff glossy peaks form, about 10 minutes. Add vanilla; mix until combined. Use immediately.