Pre-heat the oven to 170°C. Line a cupcake tin with 8 cases (see note 4).
Using an electric whisk or machine, beat the sugar and butter together until light and fluffy. Add eggs one at a time.
Running on a slow setting, add the Greek yoghurt, milk, curd and elderflower and mix until well combined.
In a separate bowl, combine the flour, baking powder and baking soda. Again, running on a slow setting, add the dry ingredients a little at a time. Stop when the flour mixture is just incorporated (do not over-work).
Dollop into the prepared cupcake tin, filling to about a ⅔ full. They do rise a fair bit, so don't fill more than this. If you are making more cupcakes than 8, just fill to the half way mark.
Bake for around 23-25 minutes, until an inserted skewer comes out clean. Leave in the pan for around ten minutes, then place on a wire rack to cool completely.