In a large bowl, massage lemon zest with sugar to release lemon oils. Add flour, baking powder and salt. Mix to incorporate all ingredients.
Grate your cold butter. Add cold butter to the large bowl with flour mixture. Use a pastry cutter or your clean hands to massage butter into the flour until the mixture resembles coarse sand particles (note: do not handle too much! more lumps of butter is better than melted butter!).
Mix together heavy cream with vanilla extract and egg. Add to your flour/butter mixture.
Mix with your floured hands a few times to moisten the dough then add your blueberries. Form into one ball and invert onto floured surface.
Gently bring dough together into 2 disks.
Cut each disk into 6 pieces and set on a plate. Brush with heavy cream and sprinkle with course (turbinado) sugar. Allow to chill in refrigerator for 15 min.
In the meantime, preheat your oven to 400°F. Line baking pan with parchment paper.
Bake scones for ~22 minutes or until the tops are set and edges are lightly golden-brown.
Allow to cool on baking tray.