Preheat the oven to 180˚C/160˚C fan/gas mark 4 and line eight cups of a muffin tin with paper liners.
Mix together the ingredients for the crust until thoroughly combined. Divide the mixture among the cups and pack down into an even layer.
Beat the cream cheese, yoghurt and sugar until smooth. Beat in the egg and vanilla extract.
Place one tablespoon of the chopped chocolate into each of the cups and top with the cheesecake batter. Divide the remaining chopped chocolate among the cups, lightly pressing them into the top of the cheesecake layer.
Bake for 20 minutes or until the cheesecakes are set. Allow to cool completely before serving.