If grating and freezing butter, do it 30 minutes before starting this recipe. If not, cut butter into small cubes.
Mix all dry ingredients: all-purpose flour, salt, sugar and baking powder.
Add butter. Using a pastry cutter, a fork or your hands, incorporate the butter into the dry ingredients. The pieces of butter should be pea-sized by the end.
Beat the egg and vanilla extract until lightly combined. Add the mixture to the dough, and stir or toss with your hands until incorporated.
Combine Greek yogurt and heavy cream, and repeat step above, mixing it just enough so the dough won’t completely form, but be crumbly with ingredients well distributed.
Add blueberries. Mix the dough just enough so they’re well distributed through it. Dough should still be crumbly.
Place crumbly dough onto a clean surface. Divide it into 2 pieces and press together lightly each piece using your hands, until it stays together in a flat disk. Some blueberries might burst, but resist the urge to add more flour if that happens.
Make the disks at least 1 inch tall.
Cut each disk into 8 pieces, and transfer shaped scones carefully to a lined baking sheet.
Refrigerate scones for 30 minutes, or while oven preheats. That will make sure scones will reach the oven in the right temperature.
Preheat oven to 400°F, rack on middle shelf.
Bake scones for about 15 minutes. Scones should be light golden on the top when ready.
Let scones rest for 10 minutes, then prepare the lemon glaze. Mix all ingredient in a small bowl: melted butter, powdered sugar and lemon juice. Stir until well combined.
Pour glaze on the top of scones with the help of a spoon.
Wait a few minutes for glaze to set and serve.