Hi Lisa I did some digging in my books and found this one for a chocolate cake with a fudge icing, you could try this one for a vegan chocolate cake, i've never made it but have used others in this book with good results, I guess if you dont want to use the fudge icing you could fill and cover with anything of your choice, hope it helps.
10oz self raising wholemeal flour
2oz cocoa powder
3tsp baking powder]9oz caster sugar
few drops vanilla essence
9tbsp sunflower oil
12fluid oz water
sifted cocoa powder (to decorate)
1oz chopped nuts (to decorate)
for the chocolate fudge
2oz soya margarine
9oz icing sugar
2tbsp cocoa powder
1-2 tbsp hot water
preheat oven to 170 c 325f gas 3
grease a deep 8" round cake tin line the base and sides with greaseproof paper and grease the paper.
sift flour, cocoa powder and baking powder into a large bowl, add vanilla and caster sugar and gradually beat in the oil and water to make a smooth batter
pour into prepared tin and smooth surface
baker in centre of oven for about 45 mins until cooked, leave in tin for 5 mins and turn out oto a wire rack peel off paper and leave to cool.
cut cake in half.
to make the frosting place margarine and water in a pan and heat until melted remove from heat add sifted icing sugar and cocoa beat until smooth and shiny allow to cool until firm enough to spread and pipe.
use 2/3 to fill and remaining 1/3 to cover sprinkle top with cocoa powder and nuts.