For the cake
- Remove the zest from the lemon using a zester and blanch in a small pan of boiling water for 1 minute. Drain then repeat the blanching process twice more, using fresh water each time.
- Drain and dry the zest.
- Preheat the oven to 180°C/350° F/gas 4. Grease and line a 900g/2lb loaf tin with baking parchment.
- Cream the butter and caster sugar together until pale, light and fluffy, then gradually beat in the eggs, a little at a time. Fold the flour into the mixture, then stir in the basil, half of the lemon zest, water and poppy seeds. Pour mixture into the loaf tin and bake for about 30–40 minutes.