In a large bowl, whisk together the flour, baking powder, cinnamon, and salt.
Grate the frozen butter and add to the flour mixture, combining until it resembles pea-sized crumbs.
In a separate bowl, whisk together 1/2 cup heavy cream, brown sugar, egg, and vanilla extract.
Pour the wet ingredients into the dry ingredients and mix until moistened.
Turn the dough out onto a floured surface and shape into an 8-inch disc. Cut into 8 wedges.
Brush the tops of the scones with additional heavy cream and sprinkle with coarse sugar.
Chill the scones in the refrigerator for 15 minutes.
Preheat the oven to 400°F.
Place the scones on a baking sheet lined with parchment paper, spaced apart.
Bake for 22-25 minutes until golden brown.
Mix confectioners' sugar and milk to make a simple icing and drizzle over the scones before serving.