Preheat oven to 190 degrees C (or 170 degrees C fan forced) and grease a deep round 28cm cake pan. Line the base with baking paper.
Combine water, white sugar, butter, cocoa and bicarb soda in a medium saucepan. Stir over heat, without boiling, until sugar dissolves. Bring to boil, reduce heat and simmer uncovered for 4 minutes. Transfer to a bowl. Cool to room temperature (this takes about 45 minutes).
Add eggs, beating well between additions. Add flour and mix a further minute until mixture is smooth. Pour into pan and bake for 1 hour or until skewer comes out clean. Cool in pan 10 minutes, then turn onto cooling rack.
When cake is completely cooled, pour over chocolate ganache.
To make the chocolate ganache; combine chocolate and cream in a small heatproof bowl. Stir with metal spoon over pan of simmering water until melted and smooth. Cool for 10 minutes, then drizzle over cake.
I found this recipe on this site about 6 months ago and have used it ever since for ganache/fondant decorated cakes. It is much lighter than a mud cake and tastes devine with good chocolate ganache. I alway baste with strawberry jam syrup before ganaching/icing(fondant) and the cake will stay moist for several days, probably even a week. - 08 May 2010