Pre-heat your oven to 160ºC/140ºC fan. Line a muffin tin with 12 cupcakes cases.
Finely grate the zest of one and a half lemons.
Put all of the cake ingredients into a large bowl (grated lemon zest, 165g self-raising flour, 1½ tsp baking powder, 3 medium eggs, 165g soft margarine, 165g caster sugar, 1½ tsp milk). Beat on a low speed (either using an electric mixer or by hand) until all of the ingredients are fully combined.
Divide the mixture equally between the 12 cupcake cases.
Bake your cakes for 20 minutes, until a skewer inserted into the middle comes out clean. Once baked, leave the cakes to cool in the tin for about 10 minutes before moving them to a wire rack to cool completely.
If you're adding the hidden lemon curd centre - Scoop out the centre of the cupcakes (take a look at my tips above the recipe for the best way to do this). Add 1 tsp of lemon curd to the centre of each cupcake.