In the bowl of a stand mixer, whisk together egg whites, sugar, ¼ cup water, and corn syrup until frothy. Place bowl over a small saucepan of simmering water. Whisk mixture constantly until sugar dissolves and a candy thermometer registers 160°, about 2 minutes. Return bowl to mixer, and beat at high speed until stiff, glossy peaks form, about 5 minutes. Beat in vanilla, and use immediately.
Recipe by Bake from Scratch at https://bakefromscratch.com/frosting-finishing-touch/