Instructions:

Whippy Icing

Source: older Fannie Farmer cookbook

In a small saucepan, cook until thick:

1 cup milk
4 tablespoons all-purpose flour

Set aside until cool.

Combine:

1/2 cup (1 stick) butter
1/2 cup shortening
1 cup granulated sugar

Beat for 4 minutes.

Add milk mixture. Beat 3 minutes. Add 1 teaspoon vanilla extract. Beat 2 minutes.