175g of unsalted butter, softened, plus extra for greasing
175g of caster sugar
Finely grated zest of 2 lemons, and juice of 1
3 British Blacktail Medium Free Range Eggs
175g of plain flour
1 tsp of baking powder
150g of blueberries
3 tbsp of granulated sugar
Preheat the oven to 180ºC, gas mark 4. Grease a 20cm round cake tin and line with baking parchment. Beat the butter and caster sugar with an electric whisk for 4-5 minutes until light and fluffy, then beat in the zest of 1 lemon. Beat the eggs together in a jug with a fork, then slowly mix into the batter, adding a spoonful of flour if the mixture starts to curdle.
Fold in the flour and baking powder until just smooth, then spoon a thin layer (about 1cm deep) of the mixture into the tin. Set aside a handful of the blueberries, then fold the rest into the remaining cake mixture and spoon into the tin. Scatter the reserved berries on top.
Bake for 30-40 minutes or until a skewer inserted into the centre of the cake comes out clean. Cover it loosely with foil if it starts to brown too much on top.
As soon as the cake is removed from the oven, pierce the top all over with a skewer. Mix the lemon juice and remaining zest with the granulated sugar and spoon all over the top. Cool completely in the tin before serving.