Pre- heat oven to 175 C. Can use dariole moulds, friand tins or medium muffin tins. Grease your moulds with cooking spray.
In a large bowl whisk together oil, yoghurt, cream, rum essence, coffee and water. Add eggs and sugar. Sift baking soda, flour and cocoa. Whisk all together until smooth. Pour into moulds to about two-thirds full . Bake for 15 minutes then insert a truffle into the centre of each cake. Make sure not to push it too the bottom or it may stick. Bake a further 15 minutes or until spongy. Can serve these with a lovely chocolate sauce.