Preheat the oven to 180 C / Gas 4. Grease a bundt cake or tube tin.
In a bowl add sugars and rosemary and rub with your fingertips till fragrant.
n a cup, add 2 tablespoons lemon juice, zest and the buttermilk and stir. Set aside. In a bowl, sift baking powder to the flour.
Crack eggs into a bowl and add the rosemary sugar. Add buttermilk mixture alternating with the flour mixture. l smooth. Gradually add the buttermilk mixture, alternating with the flour and baking powder mixture. Tip into the prepared tin.
n and bake for about 50 minutes.
Bake in the preheated oven for 50 minutes.
Let cake cool for 10 minutes in the tin then unmould. Let cool for a further 30 minutes.
Stir icing sugar and lemon juice till smooth and spreadable but not runny. Drizzle icing over cake and decorate with rosemary and lemon zest.