Melt white chocolate. Make sure it’s completely smooth! Set aside while you mix the other ingredients.
Start blending the egg whites and powdered sugar slowly in stand mixing bowl with whisk attachment until powdered sugar is combined.
Add raspberry emulsion, salt, vanilla, and dash lemon emulsion. Speed up to high until thick and glossy (about 4-5 minutes).
Add butter, a large piece at a time, while continually whisking on medium speed. Whisk until fully blended. Mixture may look a bit curdled. No worries! The next step fixes that.
Add melted white chocolate to mixture, careful not to touch sides of bowl. Make a well in the center of the bowl and pour the white chocolate into it.
Start whisk on slow & quickly increase to medium-high.
Do not let the white chocolate touch the sides of the bowl, sit for any length of time, or not get mixed in immediately or it will cool into lumps throughout the icing. Scrape it down several times until fully mixed in.
Whisk on medium-high for a few minutes, until light and fluffy.
Place in a piping bag to pipe onto the cake/cupcakes.