To begin, preheat your oven to 450 and spray a pan with non-stick spray.
To a large mixing bowl, add your flour, sugar, baking powder, cinnamon and salt and stir them together. Add your butter to the bowl and stir it in, till the butter is covered entirely by the dry ingredients.
To another bowl, add your buttermilk, vanilla and egg and whisk them together. Add your wet ingredients to your dry ingredients and stir them together till well combined. Your batter should be thick but have no flour clumps. If your batter is still too dry, and 1-2 more tbsp of buttermilk.
Use a 1/4 cup measure to scoop your dough onto your pan, for 8 biscuits total, evenly spaced apart.
To another small bowl, add together your cinnamon sugar topping. Sprinkle the mixture across the tops of your biscuits.
Bake in the oven for 10-12 minutes, or till the tops are golden and a toothpick inserted comes out clean.
While the biscuits are baking, whisk together your glaze ingredients After the biscuits come out of the oven and are cool, move them to a plate and drizzle them with the glaze.
Stored in an airtight container, these taste best within 1-2 days.