Beat butter and yoghurt together.

Beat in sugar well.

Add eggs (1 at a time and beat between).

Add vanilla.

Sift flour, cocoa, soda and salt into a seperate bowl and combine.

Fold flour mix into butter mix.

Add hot water.

Line bottom of tin with baking paper. For 1 large cake, put a layer of cardboard (like a breakfast cereal box) in bottom of tin under the baking paper.

Bake 1 hour @ 150°C, or if 2 smaller tins, bake for 45 mins.