First, preheat your oven to 170C (150C fan). Grease a loaf or cake tin with lots of butter, then line it with some baking (non-stick greaseproof) paper.
Using an electric whisk, vigorously beat together the soft butter and sugar until light and fluffy. Then, beat in the grated zest of your two lemons until fully incorporated.
Keep beating on a high speed and add the eggs, one at a time. Then, add the milk. Don’t worry if it curdles at this point – this is not a bad thing.
Weigh the flour and baking powder together, then add to your eggy buttery mix. Fold in with a large spoon until they are fully incporated – you should see no visible flour, but lumpy is fine.
Spoon into your prepared tin and bake for at least 40 minutes. To test whether it is done, stick a knife all the way through the top and it should come out clean. It should also be bouncy on the top.
Once the cake has been taken out the oven and cooled slightly in its tin, it’s time to make the syrup. Simply add the juice of your two lemons and your remaining 100g caster sugar to a pan and bring to the boil.
Make some slits in the top of the cake and pour the syrup on top evenly until it’s all gone. Leave it until totally cool, then remove from the tin and serve.
For the ultimate distribution of syrup, cut the cake in half as if you were going to layer it. Then, pour half your syrup into each layer. This will make sure your cake is thoroughly soaked. Then, you can even add some icing the middle as well!