Preheat your oven to 350°F (180°C) and line a baking sheet with parchment paper.
In a large bowl mix the flour, baking powder, salt, and sugar together.
In a second bowl, combine milk, cream, and egg.
Rub the cold butter into the flour mixture with your fingers or cut in with a pastry knife until it resembles coarse breadcrumbs.
Add the wet ingredients to the flour/butter mixture and loosely mix the ingredients until it just comes together and away from the bowl.
Turn your dough onto a floured work surface and knead a few times to create a smooth dough.
Pat your dough into a rectangle, about 7 x 10 inches.
Sprinkle the blueberries onto the surface of the dough and very gently press into the dough.
Roll up the dough, using a pastry scraper and more flour if the dough begins to stick. Pat the dough into a generous one-inch thick rectangle.
Cut out your scones with a 2 ¾ inch biscuit cutter and place on your prepared baking sheet.
Brush the tops lightly with the beaten egg glaze.
Place the scones on an upper-middle rack in your oven and bake for about 35-40 minutes, until the tops are a beautiful golden shade.
Enjoy within 24 hours. Store leftovers in an airtight container at room temperature.