In a saucepan, combine cocoa, sugar and milk.
Stirring constantly, cook over medium heat until
it reaches soft ball stage. Remove from heat.
Add vanilla and cut up candy bars.
On high speed with electric mixer,
beat until of proper spreading consistency.
Spread on cool cake.

Variation:
For optional topping, in a saucepan over low heat,
combine 1/2 sq. unsweetened chocolate cut into pieces
and 1/2 tsp. Margarine, stirring until smooth.
Remove from heat, stir in 3/4 c. confectioners' sugar
and 4-5 tsp. hot water; beat until smooth and of
drizzling consistency.
Drizzle over top and sides of frosted cake.