Preheat oven to 375°F.
Line a baking sheet with parchment paper.
In a large bowl, sift together flour, baking powder, salt and sugar.
Transfer the mixture to a stand mixer fitted with the paddle attachment. Add the cubed butter. Mix on low speed until the butter is incorporated and resembles coarse crumbs.
In a separate bowl, whisk together 1 egg, 1/2 cup heavy cream, and vanilla.
Slowly pour wet ingredients into dry mixture, mixing until just combined.
Gently fold in the blueberries, being careful not to crush them.
Turn dough out onto a floured surface.
Pat into an 8-inch circle, about 1 1/2 inches high.
Using a sharp knife or bench scraper, cut the circle into 8 equal wedges.
Arrange the wedges on the prepared baking sheet, leaving space between each piece.
In a small bowl, whisk together 1 egg and 1 tablespoon heavy cream.
Brush this mixture over the tops of the scones.
Sprinkle generously with large-crystal sugar.
Place in preheated oven and bake for 16 to 20 minutes, or until the scones are golden brown.
Remove from the oven and cool slightly before serving.