Preheat the oven to 180C (160C fan, 350F). Put the sugar and butter (or margarine) in a large bowl and beat until pale and fluffy.
Add the eggs and beat until smooth.
Add in the flour and fold through.
Add the zest of 3 lemons and the juice of 1.5 to the mixture and mix gently.
Line a 12 hole muffin tray with muffin cases and spoon the batter into the cases, aiming to fill them evenly.
Bake at for 15-20 minutes. The cupcakes should be firm and golden on top. You can check if they’re cooked through by pushing a skewer into the centre of the palest cake. It should come out clean.
In a small bowl (or saucepan), mix the juice of 2 lemons with the icing sugar. Pop in the microwave for 60 seconds (or boil on the hob) to produce a hot syrup - handle with care!
Poke holes all over the hot lemon cupcakes with a skewer to about 2/3 of the way down.
Use a spoon to spread the hot syrup all over the cooling cupcakes.
Allow to cool, then enjoy!
If you want a really crunchy topping instead of a syrup that sinks in, you’ll need to change the method slightly. Use granulated sugar instead of icing sugar and without any heat, mix your lemon juice and sugar together to form a paste, then spread over the warm cupcakes. This should give you your crunchy topping once cooled.