Lemon Cupcakes

1. Preheat the oven to 350°F / 180°C and line a cupcake tin with paper liners.
2. In a bowl, sift together the flour, baking powder, and salt.
3. In another bowl, or in the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter, sugar, and lemon zest for 2–3 minutes until light and creamy.
4. Add the eggs and vanilla extract, then beat again until fully incorporated.
5. Mix the buttermilk and lemon juice together.
6. Add the dry ingredients and the liquid mixture alternately, in 2–3 additions, mixing gently between each addition just until smooth. Do not overmix.
7. Fill the cupcake liners about ¾ full.
8. Bake for 18–20 minutes, until lightly golden and a toothpick inserted in the center comes out clean.
9. Let the cupcakes cool briefly in the pan, then transfer to a wire rack to cool completely.

Lemon Curd 

1. In a bowl, whisk together the sugar and eggs until smooth. Add the lemon juice and mix again.
2. Transfer to a saucepan over medium heat and whisk constantly until thickened. Remove from heat, add the butter, and mix until smooth. Chill completely before using.
3. Core the cooled cupcakes and fill the center with lemon curd.

Mascarpone Frosting 

1. Place the mascarpone, cold heavy cream, powdered sugar and vanilla extract in a mixing bowl or stand mixer fitted with the whisk attachment.
2. Beat on medium speed for about 2–3 minutes, until thick and firm.
3. Transfer to a piping bag fitted with a decorating tip and pipe swirls on the cooled cupcakes. Decorate with lemon zest or a lemon slice.