Preheat oven to 400 degrees then line a baking sheet with parchment paper. In a large mixing bowl, mix flour, baking powder, cinnamon, baking soda and salt until well combined.

Use a pastry cutter to cut in butter until mixture is crumbly and butter is pea-sized. In a separate bowl, mix sugar, egg and cream until evenly combined and sugar is dissolved.

Add wet mixture to the dry ingredients and stir until just combined. Form dough into a ball and roll or pat to ½" thickness. The dough will be about 9"–10" in diameter.

Cut the dough like a pizza into eight equal pieces and transfer to prepared baking sheet. Brush the tops of scones with additional heavy cream and sprinkle with coarse sugar and cinnamon.

Bake 10–12 minutes then remove from oven and allow to cool slightly on a rack. Meanwhile, stir together powdered sugar, cinnamon, milk and vanilla until glaze forms. Drizzle over scones after they have cooled slightly then serve while still warm.