Pre-heat oven to 400 degrees F. Spray a baking sheet with non-stick spray or line with parchment paper.
In a large bowl, mix flour, cocoa powder, baking powder and salt.
Add the butter, and using a pastry blender cut it into the flour until it resembles coarse crumbs (you can also use a food processor for this part, pulsing until the mixture resembles coarse crumbs).
Add the chopped chocolate and sugar to the dry mix and stir to combine.
Make a well in the center of the dry ingredients then add the sour cream and milk. Gently mix the dry ingredients into the wet ingredients. It may seem a bit dry at this point, but do not add more liquid yet.
After mixing the dry and wet ingredients, add the cherries and gently fold them in. Let sit 5 minutes. If the mixture is still dry, add milk 1 tbsp at a time until it comes together to form a dough.
Turn the dough out onto a floured counter or pastry mat and gently press into approximately a 9-inch circle (1 inch thick).
With a sharp knife, cut into 8 wedges and place them on the baking sheet.
Bake for 22 minutes until scones are risen and set. Remove to a cooling rack to cool completely.