01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together flour, sugar, baking powder, baking soda, salt, and lemon zest.
03 - Add cold butter cubes and cut in using a pastry blender or fingertips until the mixture resembles coarse crumbs.
04 - In a separate bowl, whisk together heavy cream, egg, and vanilla. Pour into dry ingredients and stir just until combined.
05 - Gently fold in blueberries. Do not overmix.
06 - Turn dough onto a lightly floured surface. Pat into a 1-inch thick round. Cut into 8 wedges and transfer to baking sheet.
07 - Brush tops with a little cream. Bake 16 to 18 minutes, until golden. Cool on a wire rack.
08 - While scones bake, make lemon curd: In a heatproof bowl set over simmering water, whisk eggs, sugar, lemon juice, lemon zest, and salt.
09 - Cook, stirring constantly, until thickened, about 8 to 10 minutes. Remove from heat and whisk in butter until smooth. Strain if desired. Chill before serving.
10 - Serve scones warm or at room temperature with a generous spoonful of lemon curd.