2 (1 oz. ea.) squares unsweetened chocolate
1 1/2 cups sweetened condensed (not evaporated) milk
1 tablespoon cold water
1 teaspoon vanilla

Melt chocolate in the top of a double boiler over hot water; blend in sweetened condensed milk.

Heat over boiling water, while stirring for 10 minutes, or until frosting is very thick.

Stir in water and vanilla; beat frosting until light. Continue to beat until the frosting is a good consistency for spreading over cake.