Preheat the oven to 400°F. Line two cookie sheets with parchment paper and set aside.
In the bowl of a food processor, add the sugar, baking powder, salt, flour, and blood orange zest. Pulse a few times to combine. Add the cold butter chunks, and pulse until you have pea-sized amounts.
Alternatively, combine all of the dry ingredients in a large mixing bowl, and then cut the butter into pea-sized pieces using a pastry cutter or the tines of a fork.
In a small mixing bowl, whisk together the egg, heavy cream, and vanilla extract. Add the cream mixture and the chocolate chunks to the flour-butter mixture, and stir with a spoon until the dough starts to come together. Use your hands if necessary, but work quickly and do not overmix! A few dry spots are ok.
Turn the dough onto a lightly floured surface, and roll until it's about 1'' thick. Use a 2 1/2'' biscuit cutter or mason jar lid to cut out the scones. Re-roll as necessary. Place the scones on the cookie sheets about 2'' apart from each other.
Alternatively, quickly press the dough into a large 1'' thick circle. Cut into 1/8ths with a sharp knife.
*Optional: Place the scones in the fridge or freezer for about 10 minutes to ensure the butter is cold before baking!
Bake the scones for 10-12 minutes, until the bottoms are a light golden brown and the tops are dry. Let the scones cool on the pan for about 5 minutes, and then transfer the scones to a wire rack to cool completely.