Step 1

Preheat oven to 160°C. Grease a 20cm round cake pan and line the base with non-stick baking paper. Combine the butter, chocolate, oil, sugar and 1 cup (250ml) water in a saucepan. Stir over a medium-low heat until melted. Stir in the vanilla essence and set aside to cool.

Step 2

Sift the dry ingredients into a large bowl. Add the cooled chocolate mixture and eggs. Stir gently until just combined. Pour into the pan.

Step 3

Bake for 1 hour 15 minutes to 1 1/2 hours or until a skewer comes out clean when inserted. Set aside in the pan for 10 minutes, before turning out onto a wire rack to cool completely.

Step 4

Place the cream and extra chocolate in a saucepan. Stir over a low heat until melted. Transfer to a bowl and set aside until it thickens slightly. Pour over the cake and serve.