Preheat the oven to 400°F. Line a large baking sheet with parchment paper.
In a large bowl, whisk together the flour, sugar, baking powder, cinnamon, and salt. Zest the lemon into the dry ingredients.
In a separate bowl, whisk together the milk, egg, vanilla extract, and juice of the whole lemon. Set aside.
Place the cold butter cubes in the bowl of dry ingredients. Toss to coat them in flour, then use your hands or a pastry cutter to break apart the butter pieces and blend them into the flour. Keep cutting the butter into the flour until the pieces are small and the mixture looks like sand. Work quick to avoid the butter melting.
Pour the wet mixture into the dry ingredients and stir with a rubber spatula just until combined. Gently fold in the blueberries until evenly dispersed. The dough will be quite sticky. Add flour, 1 tablespoon at a time, if it is too sticky to handle.
Flour a surface and turn the dough out of the bowl. Flour your hands and press the dough together into a circle about 8-inches wide and ½-¾" thick. Cut into 8 slices and transfer the scones to a baking sheet lined with parchment paper. Press a few blueberries on top for presentation. Brush the tops with milk and sprinkle with coarse sugar. If the dough is feeling soft, chill the scones for 15-20 minutes until firm.
Bake for 21-22 minutes, until firm with a light golden colour. Scones made with frozen blueberries may take 2 minutes longer. Allow the scones to cool on the baking sheet for 15 minutes before transferring to a wire cooling rack. Enjoy warm or allow to cool before icing.
Stir the glaze ingredients together in a small bowl. Use a spoon to drizzle over the cooled scones while they are still on the wire rack. For easy clean up, place a piece of parchment or aluminum foil under the rack. The icing will dry in about 10 minutes. Scones are best enjoyed fresh!