Procedure
In a dry bowl mix butter and sugar in one direction till its fluffy
In a separate bowl mix all ur dry ingredients (flour,
preservative, milk flavor, baking powder).
In another bowl whisk ur eggs, butter scotch.
Pour your egg mixture into the mixed butter and sugar and stir till it is equally mixed.
Start adding your dry ingredients till you are satisfied.
Cream your pans with butter and pour your banter into them.
And put in a pre heated oven for about 50mins.

Get a clean bowl and add you icing sugar and margerine
Mix with you electric mixer
Add water, flavour, colour of your choice and mix until mixed
Prepare your pipping bag, and decorate the cake