Preheat the oven to 180°C/160°fan/Gas 4. Line a 12-hole muffin tin with paper cake cases.

Tip the butter, caster sugar, flour, eggs and milk into a bowl and beat until smooth. Beat in the lemon zest. Divide the mixture between the paper cases.

Bake the cakes for 15-18 minutes or until they have risen and are a light golden colour and spring back when lightly pressed. Transfer to a wire rack.

Mix the granulated sugar with the lemon juice and spoon over the hot cupcakes. Sprinkle with more lemon zest, if you like.

These cakes can be eaten when they are still slightly warm or left to cool completely.