01 - Preheat oven to 400°F. Line baking sheet with parchment paper.
02 - Whisk together flour, sugar, baking powder, salt, and Vietnamese cinnamon in large bowl.
03 - Add cold cubed butter to dry mixture. Cut in using pastry cutter or fingers until mixture resembles coarse crumbs.
04 - Whisk together heavy cream, egg, and vanilla extract in small bowl.
05 - Pour wet mixture over flour-butter mixture. Gently fold until just combined. Carefully fold in blueberries to avoid crushing.
06 - Turn dough onto lightly floured surface. Pat into 7-8 inch circle, about 1 inch thick.
07 - Cut into 8 wedges. Place on prepared baking sheet, slightly apart.
08 - Brush tops with extra cream. Sprinkle with coarse sugar and pinch of cinnamon if desired.
09 - Bake 18-22 minutes until golden and firm.
10 - Cool 10 minutes before serving.