Chocolate Slice with Marshmallow Topping

Base
3 Weetbix
1 cup SR flour
2 tabs margarine
1 dspn cocoa
½ cup sugar
1 cup coconut

First topping
2 T cocoa
2 T butter
8 T icing sugar (approx)

Marshmallow
1 ½ d gelatin + C hot water
1 ½ C sugar

Final Topping
90 g copha
½ C drinking chocolate (or less cocoa)
Melt butter, add dry ingredients, crushing Weetbix well. Press into tin. Bake 15 mins in moderate oven. Ice with first topping when cool. Melt gelatin in hot water, pour into saucepan and add sugar, boil for 1 minute. Cool, then beat until fairly stiff and pour over biscuit. Melt copha, remove from stove and add chocolate. Cool and pour over marshmallow.