Preheat oven to 425 degrees F and line a large baking sheet with parchment paper.
In a large mixing bowl mix together the flour, sugar, baking powder, salt, and lemon zest until fully combined. Grate the frozen butter on a box grater and add the butter to the flour mixture. Use a large fork to combine the butter with the flour, finishing with your fingers until the mixture resembles course meal. Set aside.
In a separate bowl whisk together the half and half, egg and vanilla extract. Pour it over the flour mixture and use a large rubber spatula or wooden spoon to combine until wet and dry ingredients are just combined. Very carefully fold in the blueberries. Although the dough will be wet and sticky, do not over work the dough.
With floured hands, gather the dough and work it into a ball as best you can on a clean floured surface. Press the dough into an approximate 8-inch circle disc and cut into 8 equal slices.
Carefully transfer scones to prepared baking sheet at least 1-2 inches apart. Brush the top of each scone lightly with a thin layer of half and half or cream and bake for approximately 18 minutes.
Remove from the oven and allow to cool on a cooling rack. In the meantime, prepare the icing. Whisk together the confectioners' sugar with the lemon juice in a small bowl. Once the scones have cooled, spread or drizzle 1-2 teaspoons of icing over the top of each one.