Prepare cake mix and bake in 2 layer pans according to package directions. Cool.
Meanwhile, mash 4 bananas in a saucepan; add sugar and 1/4 cup lemon juice. Cook, stirring constantly until mixture comes to a full boil. Chill; fold in whipped cream
Combine 1/2 cup semi-sweet chocolate pieces and butter in saucepan; cook over low heat, stirring constantly until smooth.
Beat egg until frothy; gradually stir in chocolate mixture and beat until smooth. Chill until spreading consistency.
Spread about 1/3 of banana cream between cake layers. Spread chocolate glaze over top of the cake. Frost sides with remaining banana cream.
Just before serving, halve 2 bananas and brush with lemon juice; insert chocolate pieces for eyes and licorice for mouths. Insert toothpicks in cut parts of bananas and secure spooks to top of the cake. Secure marshmallow cat faces on toothpicks and insert around sides of the cake.