Anya, here is a choc cake recipe I make on a regular basis,so know it's good.
300 gram. Soft Stork marg
300 gram caster sugar
4 large eggs
300 gram Dove SR gluten free flour
Teaspoon gluten free baking powder (it will work without it though)
Teaspoon vanilla extract( it will work without this too)
3tablesp.cocoa powder, Green and Blacks is good.
3tablesp. Milk.
Mix sugar and butter first then add the dry things, plus beaten eggs,and milk and van extract.make sure the mixture is slightly gloopier than a normal dropping consistency, if not add a drop more milk. Cook as a normal sponge cake, in either one or two cake tins.
Make usual choc butter icing fir inside and melted choc on top. This makes a lovely cake and it tastes as a normal cake would.