Pre-heat the oven to 180° C.
Grease and line a 2lb straight-sided loaf tin with nonstick baking paper.
In a large mixing bowl, cream together the butter, sugar and vanilla extract until light and fluffy. Beat in the eggs, one at a time, mixing well between additions. Fold in the flour, baking powder, cinnamon and yogurt until incorporated, then add the chunks of apple, mixing well.
Spoon into the prepared loaf tin and bake for 70-80 minutes; it is ready when a cake tester comes out clean from the centre of the loaf cake. Remove and allow to cool in the tin for 10 minutes before turning out.
Transfer to a wire rack to cool completely and finally dust with the icing sugar once cool.