Step 1

Add the white chocolate chips and 1/3 cup of milk to a glass, microwave safe bowl. Heat in the microwave at 50% in 30 second intervals, stirring each time, until the the white chocolate is smooth. Allow to cool.

Step 2

Cream butter until light and fluffy, about 3 minutes. Stir in melted and cooled white chocolate and then gradually add in confectioner's sugar, about 1 cup at a time. Then add in milk, 1 tablespoon at a time, followed by vanilla. Beat on high for about 1 to 3 minutes until the buttercream frosting is smooth, fluffy and will hold a peak.