• Line a large sheet pan with parchment paper and make room in the freezer for the pan. You can use two small pans if needed. Set aside.

Mix the Wet Ingredients

• In a large spouted measuring cup, whisk the discard, cream, one egg, vanilla, lemon zest and juice until smooth. Set aside.

Mix the Dry Ingredients

• In a large mixing bowl, whisk the flour, corn starch, sugar, baking powder and salt.

Mix the Scones

• To the flour mixture, grate in the cold butter (just from the fridge) using the largest holes on a grater. Toss the butter with the flour just to coat the butter. To the butter and flour mixture, add the blueberries and toss until evenly distributed.

  The butter should remain cold and pliable throughout the mixing process. If the butter starts getting melty, pop the whole bowl in the freezer (before adding any liquid) for about 10 minutes.
• Working quickly, make a well in the center of the flour mixture and pour in the wet ingredients. Use a silicone spatula to gently stir the mixture until the flour is just moistened. There still should be some dry patches of flour.

  Use your hand to gently scoop the dough up and fold it over (gently pressing) on top of itself. Do this 10-12 times (this helps build layers) attempting to work the dough so that the blueberries stay whole rather than squished. The dough will be a shaggy mess.
• Transfer the dough to a floured work surface and gently knead/press the dough together to form a disk. Work gently, but quickly as the dough needs to stay cold.

  Roll the dough out to 3/4 - 1 inch (1.9 -2.54 cm) thick disk (7 1/2 - 8 inches wide / 19-20cm). If a few of the blueberries popped on the surface, sprinkle them with a bit of flour and continue rolling.

  *Optional: if it's warm in your kitchen and the dough is super soft, transfer the disk to a parchment lined sheet pan and pop in the freezer for 15 minutes. The colder the dough the easier it is to make a clean cut which results in scones that rise evenly.

  Remove the dough from the freezer and cut into eight wedges using a knife in one quick motion down. No sawing here.
• Arrange the scones evenly apart on the parchment lined sheet pan(s), and place in the freezer for 30 minutes.

  Make Ahead: At this point, scones may be frozen solid for a quick bake in the morning or for longer storage. If freezing for next day or longer be sure to store frozen scones in a container or freezer bag.

Bake the Scones

• Arrange an oven rack in the center of the oven and preheat the oven to 425 Fahrenheit (218 Celsius).

  Just before baking, crack the remaining egg in a small bowl and whisk with a tablespoon of water. Use a pastry brush to lightly brush the top of the scones with the egg wash then sprinkle with turbinado sugar.
• Bake the scones at 425 Fahrenheight for five minutes, then turn the oven down to 375 Fahrenheight (190 Celsius) and continue baking for 20-25 minutes more. The internal temperature will be between 200-205 Fahrenheight when done (93-96 Celsius), and the tops will be golden brown.

  Cool slightly, then share warm simply or with blueberry jam or clotted cream.

  Tip: For a dryer scone, turn the oven off, leave the scones in the oven, and prop the oven door open for about 10 minutes.

Store the Scones

• Store covered at room temperature for up to two days.

  To Freeze Before Baking: Freeze scones individually on a sheet pan, then transfer to a freezer bag or storage container for up to two weeks. Frozen scones can go straight from freezer to oven baking a few minutes longer if needed.

  To Freeze After Baking: Allow scones to cool completely before freezing. Freeze scones individually on a sheet pan, then transfer to a freezer bag or storage container for up to two weeks.

  To Rewarm: Thaw at room temperature, then rewarm scones in a 350 Fahrenheight oven for about 10-15 minutes.