Preheat the oven to 200 °C | 400 °F. Line a baking sheet with parchment paper.
In a large mixing bowl add cream, buttermilk, vanilla essence and whisk well. Set aside.
In another bowl, add all-purpose flour, whole wheat flour, cocoa powder, sugar, baking powder, salt and mix well.
Using a grater with large holes, grate the butter into the flour. Using your fingers, rub butter into flour until the mixture becomes coarse.
Add this mixture into the wet ingredients and mix with a fork until just incorporated. Add the chocolate chips and gently press to form a dough.
Place on a lightly floured surface. Gently roll to a circle of ¾th inch thickness. Cut into 6 triangles and place on the baking sheet about 1-inch apart.
Bake for 20-25 minutes or until cooked. Place them on a wire rack and allow to cool for 5 minutes.
To make the chocolate drizzle, melt the chocolate and butter in the microwave. Whisk until smooth. Drizzle over the warm scones.
