Preheat the oven to 160C (320F) fan-forced

Grease a 20cm (9 inch) square cake pan and line it with baking paper.

Place the flour, baking powder and salt in a large bowl and stir them together. Add the butter and using your fingertips, rub the butter though until it forms a texture like fine breadcrumbs (or use a food processor).

Add the sugar and stir it through.

Take half of this mixture and tip it into the tin. Press it into the tin.

In a small bowl, add the sour cream and baking soda and stir it through until it has dissolved. Add the beaten eggs and nutmeg then add them to the other half of the flour mixture.

Mix it all together well then pour it into the tin.

Dust the batter with a little cinnamon.

Bake the cake for 45 to 60 minutes or until a cake tester comes out clean.

Leave it to sit in the tin for 10 minutes before transferring it to a wire rack to cool.

Dust with icing sugar to serve.