In a small bowl, toss blueberries with a little bit of flour, until they are lightly dusted. Set aside.
In a large bowl, combine all the dry ingredients. Mix well.
Using a cheese grater or box grater, grate the chilled butter into the dry ingredients. Work quickly so the butter does not melt.
Using a pastry cutter or your hands work the butter into the dry ingredients until it becomes crumbly.
In a small bowl, beat the egg with the milk. Add to the flour and butter mixture.
Add lemon juice and lemon zest.
Mix the ingredients until a ball of dough forms. If it is too sticky, add a little more flour. If it is too dry, add a little milk. It should be sticky but not so much that you can't work with it.
Divide the dough in half. On a well-floured surface, roll each half out into 7-inch circles.
Sprinkle the blueberries over one of the circles. Place the other circle over the top and pat down gently (don't squish the berries!) until the circles are meshed together. Flatten out the circle until it is about 12 inches.
Cut into 8 slices, like a pizza. Place on a lightly greased baking sheet and chill in the fridge for about 15 minutes.
While the dough is chilling, preheat the oven to 450.
When the dough is chilled and the oven is preheated, take the dough from the fridge and brush the top of each scone with heavy cream. Sprinkle a little bit of sugar over the top of the cream.
Bake the scones for 12-15 minutes, or until the tops are just slightly golden brown.
Take the scones out of the oven and place the baking sheet on a cooling rack.
While the scones are cooling, make the glaze by combining the lemon juice and powdered sugar. If it is too thin, add more powdered sugar. If it is too thick, add more lemon juice or milk.
When the scones are cooled completely, drizzle glaze over the top and serve.