01 - Preheat the oven to 400°F and line a baking sheet with parchment paper.
02 - Whisk together flour, sugar, baking powder, baking soda, salt, and lemon zest in a large bowl until thoroughly combined.
03 - Add cold butter cubes to the flour mixture. Using a pastry cutter or your fingertips, work the butter into the dry ingredients until the texture resembles coarse crumbs with some pea-sized pieces remaining.
04 - Gently fold the fresh blueberries into the flour-butter mixture, taking care not to crush the berries.
05 - Whisk together the heavy cream, egg, and vanilla extract in a small bowl until uniform.
06 - Pour the cream mixture over the flour mixture and mix gently with a fork just until the dough begins to come together. Do not overmix as this will result in tough scones.
07 - Turn the dough onto a lightly floured surface and knead once or twice to bring it together. Pat into a 1-inch thick round disc and cut into 8 equal wedges.
08 - Transfer wedges to the prepared baking sheet. Brush tops lightly with additional cream. Bake for 18 to 22 minutes until golden brown and a toothpick inserted in the center comes out clean. Cool on a wire rack.
09 - Whisk together eggs, sugar, lemon juice, and lemon zest in a small saucepan over medium-low heat.
10 - Cook the mixture, whisking constantly, until it thickens and coats the back of a spoon, approximately 5 to 7 minutes. Do not allow the mixture to boil.
11 - Remove from heat and whisk in butter until smooth and melted. Strain through a fine sieve into a clean bowl. Let cool to room temperature before serving.
12 - Serve scones warm or at room temperature with a generous spoonful of lemon curd.