Preheat oven to 400F/200C. Line a large baking sheet with parchment paper or a silicone baking mat. Set aside.

In a large bowl, toss together sugar and lemon zest. Add flour, baking powder, salt, and sugar, and whisk to combine. Cut in butter using a pastry blender until mixture resembles coarse meal. Alternately, you can pulse the ingredients in a food processor. Having uneven pieces of butter throughout is ok. Gently stir in blueberries until coated with flour.

In a small bowl, whisk together egg, ½ cup heavy cream, and vanilla extract, then add it to the flour mixture. Gently toss with a rubber spatula until dough begins to form. Don’t over mix. Transfer dough to a floured surface and knead gently, about 5-6 times, until a ball forms. The dough might be slightly sticky. Pat dough into a 9-inch (22 cm) circle, about ¾-inch thick, and cut into 8 even wedges.

Place scones on prepared baking sheet. Brush tops with a bit of heavy cream and sprinkle with coarse sugar. Bake for 15-18 minutes, or until golden brown and a toothpick inserted into the center of the scone comes out clean. Transfer baking sheet to a wire rack and allow to cool for 10 minutes. While scones are still hot, sprinkle again with coarse sugar for extra crunchiness.

Scones are delicious either warm or at room temperature.

Scones are best eaten the same day they are made, but they can be frozen for up to 1 month.