(click on the text to highlight each stage):

1. Preheat the oven to 180°C/160°C Fan/ Gas 4. Grease and flour a 20 cm spring form cake tin. Cream the butter with 110g Golden Caster sugar until light and creamy.
2. Whisk in the egg yolk.
3. Sift together the flour and cornflour and fold into the mixture.
4. Whisk the egg whites until they form soft peaks and whisk in the remaining sugar.
5. Gently fold half this meringue into the cake mixture until incorporated, then fold in the other half with the rosemary.
6. Spoon into the prepared cake tin and bake for 30-35 minutes.
7. Cool in the tin for 15 minutes then turn out onto a wire rack to become cold.
8. Dust the top of the cake with Golden Icing sugar and decorate with sprigs of rosemary.