Mix together the cocoa, cinnamon, vanilla and sugar in a dry bowl. Put the baking soda to become effervescent in the yoghurt. Beat the yoghurt with the oil, and then gradually add the flour and other dry ingredients.
Add dried fruit of your choice and beat until uniform. Pour the mixture into a pre-greased and floured oven dish or baking tray. Put it to bake in a moderate oven and check its readiness with a toothpick.
Sprinkle the ready cinnamon cake with powdered sugar.