Ingredients
5 large egg whites
1 1/4 cups sugar
2 cups (4 sticks) unsalted butter, room temperature, cut into pieces
1 teaspoon pure vanilla extract
1/4 teaspoon coarse salt
Preparation
Combine egg whites and sugar in the heatproof bowl of an electric mixer. Set the bowl over a pan of simmering water. Whisk constantly until sugar has dissolved and whites are hot to the touch, about 5 minutes.
Transfer the bowl to the electric mixer. Using the whisk attachment, beat until stiff, glossy peaks form, about 10 minutes.
At low speed, add butter, one piece at a time, to egg whites, and beat until smooth. Add vanilla and salt, and beat to combine.
