Step 1

Preheat the oven to 400°F and set an oven rack in the middle position. Line a 13 x 18-inch baking sheet with parchment paper.

Step 2

In a large bowl, whisk together the flour, salt, baking powder and sugar. Add the pieces of cold butter. Use your fingertips to rub the butter into the dry ingredients until the mixture resembles coarse crumbs with pea-sized clumps of butter within. Stir in the blueberries.

Step 3

In a small bowl, whisk together the heavy cream, egg and vanilla. Make a well in the center of the dry ingredients, then add the cream mixture. Using a rubber spatula, mix until the dough comes together. It will be a bit crumbly—that’s okay. If it’s too dry to come together, add 1 to 2 tablespoons more cream and mix again.

Step 4

Dust a work surface lightly with flour; put the dough on top. Dust the dough lightly with flour, then knead gently into a ball. Press the dough into a circle about ¾-inch high, then cut into 8 wedges. It’s okay if you slice through some of the blueberries.

Step 5

Place the unbaked scones onto the prepared baking sheet at least 1-inch apart. Beat the remaining egg in a small bowl and use it to brush the tops of the scones (you won’t use all of it). Bake for 17 to 20 minutes, until golden and firm to the touch. Transfer the scones to a wire rack to cool. Slide the used parchment paper underneath the rack. (The parchment will catch any drips from the glaze).

Step 6

While the scones cool, make the glaze: In a small bowl, whisk together the melted butter, confectioners’ sugar, and lemon juice and zest. When the scones are completely cool, drizzle the glaze over top. (Hint: if the glaze seems too stiff to drizzle, warm it in the microwave for 5 to 10 seconds.) Let the glaze set, then serve.