Make simple syrup: Combine 1/4 cup hot water with 1 1/4 cup sugar. Stir until sugar has dissolved. Set aside.

Place egg whites and cream of tarter in a stand mixer. Turn on medium high and whip until soft peaks form. About 3-4 minutes.

Take 3/4 cup of the simple syrup you made and add in 1/3 cup water and 2/3 cup sugar. Stir to combine and sugar has dissolved.

With your mixer on low speed, pour the sugar water mixture in a steady stream. Then turn mixer to high and whip until peaks form and mixture is glossy and thick. About 7-8 minutes.

Add in vanilla and continue whipping for 1-2 minutes.

Store in the refrigerator for up to 3 weeks.