Microwave the white chocolate in a microwave-safe bowl in 20-second intervals, stirring, until melted; set aside.
Beat the cream cheese, butter, confectioners' sugar and vanilla in a large bowl with a mixer on medium speed until smooth and creamy, about 4 minutes.
Gently fold in the melted white chocolate with a rubber spatula.
(The frosting can be refrigerated, covered, for up to 2 days. Beat with a mixer to soften just before frosting the cake.)
Source:
Taste of Home