Preheat your oven to 180°C (350°F) and line 22 cupcake liners in two standard cupcake pans.

In a large bowl, mix together the castor sugar and lemon zest. Add softened unsalted butter and cream until fluffy.

Add the eggs one at a time, incorporating the vanilla extract.

In another bowl, sift together cake flour, baking powder, and salt. Combine this dry mix with the wet ingredients, alternating with sour cream.

Fold in chopped pistachios.

Fill cupcake liners two-thirds full and bake for 15-20 minutes until golden and a toothpick comes clean.

In a small saucepan, heat raspberries, sugar, and lemon juice until softened, then cool and transfer to a piping bag.

Beat icing sugar and butter to a crumbly texture, then add cream cheese and pistachio butter until smooth. Optionally, add green food coloring.

Once cooled, core cupcakes and fill each with raspberry purée, then top with pistachio buttercream and garnish.