In a mixing bowl combine sourdough discard, half and half, 1 egg, vanilla, and brown sugar.

In a separate large bowl whisk together the flour, salt, and baking powder.

Grate the frozen butter using a cheese grater over the flour mixture. Using a pastry cutter or fork, mix the butter until it is evenly distributed and the mixture starts to form pea sized clumps.

Pour the wet ingredients into the dry ingredients and mix using a wooden spoon or rubber spatula until the flour is mostly incorporated. The dough will be wet and sticky.

Using damp hands, fold the dough over itself 10 times, adding in the blueberries 1/3 cup at a time.

Dump the dough out onto a lightly floured surface and knead about 10-12 times. Shape into a thick circle about 8 inches in diameter.

Using a sharp knife or pastry scraper, cut the dough into 8 even pieces. Dip the knife or scraper into flour for each cut to avoid sticking.

Place the scones on a sheet pan or plate and place in the freezer for 40 minutes.

While the scones are in the freezer, preheat the oven to 425 degrees and line a baking sheet with parchment paper.

Using the one remaining egg, make an egg wash. In a small bowl beat the egg and add 1 tablespoon of room temperature water.

Once the scones are done in the freezer, lightly brush a thin layer of egg wash on each scone. You do not want the egg wash to drip down the sides.

Place the scones onto the baking sheet evenly spaced and bake for 5 minutes at 425 degrees. After 5 minutes reduce the oven temperature to 375 and continue to bake for 20-22 minutes or until the tops are a golden brown.

Once the scones are done baking, transfer them to a cooling rack.