For the Cake:
2 1/4 cups cake flour 335g
1 1/4 cups granulated sugar 235g
1 tsp baking powder heaping
1 tsp kosher salt
2/3 cup whole milk 160ml, room temperature
1/4 cup sour cream 60ml, room temperature
6 large egg whites room temperature
3 tbsp elderflower syrup
Lemon zest
1/3 cup lemon juice 80ml
¾ cup unsalted butter 176g, room temperature
For the Lemon Curd:
6 egg yolks
⅓ cup lemon juice 80ml, freshly strained
1/2 cup unsalted butter 115g, chilled
1 cup granulated sugar 228g