Place egg whites and sugar in the bowl of an electric mixer. Gently whisk to combine.
Place mixing bowl over a medium saucepan of water to create a double-boiler.
Whisking constantly, heat on medium-high until the egg mixture is hot to the touch (about 160 degrees F on candy thermometer)
Transfer the bowl back to the stand mixer and beat on high with the whisk attachment.
Continue to mix until the bowl become room temperature.
Stop the mixer and swap out the whisk attachment for the paddle.
With the mixer on medium-low, add in the vanilla and butter, a few tablespoons at a time.
Continue to mix until light and smooth.
Add in the rose flavor to your liking and the pink color (optional).
Mix until everything is fully incorporated.