Preheat oven to 325°F. Zest the lemon directly into the sugar and set aside. The longer it sits, the more pronounced the lemon flavor will be.

In the bowl of a stand mixer fitted with the paddle attachment, combine the flour, lemon sugar, salt, and baking powder. Mix briefly to distribute. Add the cold cubed butter and mix on low until no visible butter pieces remain and the mixture resembles damp sand.

Whisk or blend the vanilla, eggs, and cream together until smooth. With the mixer running on low, pour the cream mixture in slowly and mix until almost incorporated.

Turn the dough out onto a clean surface and knead gently just until it comes together with no dry spots. Add the blueberries and fold them in carefully.

Roll the dough into a rectangle about ½ inch thick. Cut into 4-inch strips, then into squares, then diagonally into triangles. Press any scraps together and cut additional scones. Transfer to a parchment-lined baking sheet.

Chill the shaped scones completely before baking. To bake from frozen, skip thawing and add two to three minutes to the bake time.

Brush scones with heavy cream and sprinkle with turbinado sugar. Bake for about 15 minutes, until golden brown around the edges, puffed, and the centers offer slight resistance when touched. Cool on the baking sheet or serve warm.