CRISCO STAY SOFT CHOCOLATE FROSTING

1/4 cup unsweetened cocoa powder
2 tablespoons cornstarch
3/4 cup sugar
1 cup milk
1 teaspoon vanilla
1 teaspoon butter

Mix together cocoa powder, cornstarch and sugar. Add milk and cook slowly until thickened, stirring constantly. Remove from heat. Add vanilla and butter. Stir gently until cool and thick enough to spread.

From: Recipelink.com
Source: Recipe booklet: Recipes for Good Eating, The Procter and Gamble Company, 1945