In a large bowl, whisk together flour, sugar, baking powder, cinnamon, and salt. 

Using a box grater, grate the frozen butter and add it to the flour mixture, using a pastry cutter or your fingers to combine. Combine until the dough forms pea sized crumbs.

In a small bowl, whisk 1/2 c. of heavy cream, egg, and vanilla extract together. Drizzle this over the flour mixture and add the blueberries, mixing together until the dough appears moistened. 

Lightly flour your work area and move the dough to the floured space. Using your hands, work the dough into a ball, it will be stick. If it's too sticky, you can add a little more flour, or 1/2 tbsp. of heavy cream if the dough is too dry. 

Press the dough into an 8" round and use a knife or bench scraper to cut it into 8 wedges, like a pizza. 

Brush the wedges with heavy ceam and sprinkle with coarse sugar, if desired. 

Place the wedges on a baking sheet lined with parchment paper and refrigerate for 15 minutes. 

Preheat oven to 400°F. 

Remove the wedges from the refrigerator and bake for 22-25 minutes, or until they are golden brown around the edges and light brown on top. 

Remove from the oven and allow to cool for a few moments before topping with vanilla icing, if desired.