Preheat oven to 400°F. Line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, granulated sugar, baking powder, and salt.
Using your hands, mix in the slices of cold butter until the dough is crumbly.
In a separate bowl, whisk together the coconut milk, egg, vanilla, lemon zest and lemon juice.
Add the wet ingredients to the dry ingredients, whisking and then using a silicone spatula to fold together until just combined.
Gently fold in the blackberries.
On a lightly floured surface, turn out the dough and form a round disc about 9 to 10 inches in diameter.
Slice the disc into 8 equal triangles, and place onto the prepared lined baking sheet, about 2 inches apart from each other.
Bake at 400°F for 15 to 20 minutes. While the scones are baking, make the glaze.
Make the blackberry glaze
In a small saucepan, add the blackberries, lemon juice and bring to a boil. Boil for 2 minutes, until the blackberries start to soften.
Remove from the heat and pour into a blender. Blend for 1 to 2 minutes, then strain through a sieve over a large bowl.
To the remaining blackberry liquid in the large bowl, whisk in the powdered sugar, ½ cup at a time. Whisk until the glaze reaches your preferred thickness. If you want a thinner glaze, use less powdered sugar. If you want thicker glaze, add a little more powdered sugar.
Assemble the scones
Allow the scones to cool on the pan for 10 minutes then transfer to a cooling rack and once cool, glaze with the blackberry glaze and sprinkle sanding sugar over each scone.
Video
Notes
Storage: Store unglazed scones in an airtight container at room temperature for up to four days, or store glazed scones in an airtight container in the refrigerator for up to 3 days.