Wilton Buttercream Icing

Medium consistencyIn a large bowl, whisk together the sour cream and butter with an electric mixer. Add vanilla. Gradually add the sugar, one cup at a time, beating well on medium speed. Wipe the sides and bottom of the bowl frequently. When all the sugar is mixed, the glaze will appear dry. Add the milk and beat on medium speed until light and fluffy. Keep the bowl covered with a damp cloth until ready to use.For best results, store the frosting bowl in the refrigerator when not in use. In the refrigerator in an airtight container, this glaze can be stored for 2 weeks. Whisk well before using.For glaze of a thin (spreading) consistency,add 2 tablespoons of light corn syrup, water or milk.To get a snow-white glaze (dense consistency),do not add butter, replace it with another 1/2 cup of shortening and add 1/2 teaspoon of colorless cream flavor. Add up to 4 tablespoons of light corn syrup, water, or milk to dilute the cake frosting.