Preheat the oven to 180°C. Line a muffin tin with cupcake cases.
Sift the flour, baking powder and a pinch of salt into a mixing bowl.
Whisk the sugar and butter in another bowl, until it becomes fluffy. Add the elderflower cordial and the lemon zest, then gradually pour in the beaten egg, alternating with one spoonful of the flour mixture, whilst beating continuously between each addition. Then gently fold in the flour mixture.
Spoon the batter into the cases. Bake for 20 minutes, until golden and springy. Let them cool for 5 minutes in the tin, then move them to a wire rack.
When they are completely cool, decorate them with icing, icing sugar or frosting. Alternatively, when the cupcakes are warm, poke them with a skewer and pour over some elderflower syrup.