1. Preheat the oven to 160°C (fan). Line 12-hole cupcake tin with cupcake cases and set aside.
2. In a large bowl, cream together the butter and caster sugar, until pale and fluffy, about 3 minutes. Add Lyles Golden Syrup and mix again to combine.
3. Add eggs, one at a time, mixing well after each addition. Scrape the sides and the bottom of the bowl as and when needed.
4. Fold in the flour and lemon zest and stir to combine until you have a smooth, thick batter.
5. Divide the batter between the cupcake cases and bake for 18-20 minutes, until golden and the toothpick inserted in the middle comes out clean. Remove from the oven and cool the cupcakes completely.
6. Meanwhile, prepare the buttercream. Place the butter in a bowl of a standing mixer, or a hand-held electric mixer and whip it until pale and fluffy, about 3 minutes. Add the icing sugar in two separate additions and mix well. Add the lemon juice and mix again. If the buttercream feels too soft, add a little bit more icing sugar, if it feels too stiff, add more lemon juice. Transfer to a piping bag fitted with a decorative nozzle and set aside.
7. Once the cupcakes have cooled completely, scoop out a small hole in the top middle of each cupcake (use a small knife or a teaspoon), and fill with roughly about ½ tbsp of lemon curd.
8. Pipe the lemon buttercream swirls on top of each cupcake, and sprinkle with some additional lemon zest to finish (optional). Enjoy!
