Preheat oven to moderate 180oC.
Brush a 20cm round spring form tin with melted butter or oil, line base
and side with paper, grease paper.
Using electric beaters, beat butter,
sugar and cinnamon in small mixing bowl at medium
speed until light and creamy.
Add egg, beat 1 minute or until just combined.
Add the apple, sifted flour and milk, beat at low speed
1 minutes or until mixture is smooth.
Pour mixture evenly into prepared tin; smooth
surface. Bake for 30 minutes or until skewer comes out clean when
inserted in centre of cake.
Leave in tin 10 minutes before turning
onto wire rack to cool.
To make Cinnamon Topping -
Combine all ingredients in a small pan. Stir constantly over low heat
until mixture boils and sugar has dissolved, for 2 minutes.
Using a flat-bladed knife, spread the
warm icing over the top of the warm cake.