This is a basic cream cheese frosting with white chocolate mixed in! An easy way to incorporate white chocolate into a frosting.
In a heat proof bowl over a pan of simmering water, gently melt the white chocolate. Allow to cool for 10 minutes or so.
Using an electric mixer, beat the butter at medium speed until creamy. Add the cream cheese and beat until combined.
Beat in the melted white chocolate.
Add the vanilla and 2 cups of powdered sugar and beat at low speed, scraping the sides and bottom of the bowl, until light and fluffy.
Add more powdered sugar to arrive at the consistency and sweetness you like. 2 cups worked for me.