Instructions

1. Chocolate cupcakes
   Preheat oven to 180 C (350 F) standard / 160 C (320 F) fan-forced. Line a 12 hole muffin tin with cupcake cases.
2. In a large mixing bowl, add flour, cocoa powder, baking soda, baking powder and sugars – give it a little stir.
3. In a separate mixing bowl, add melted butter, eggs, vanilla and buttermilk and whisk together briefly – just to break up the egg yolks. Add the wet mixture to the dry mixture and gently fold until just combined.
4. Spoon the mixture into the prepared cupcake liners (approximately 2/3 full) and pop into the oven. Bake for 18-20 minutes or until just cooked through. Transfer cakes out on a wire rack and leave to cool completely.
5. Marshmallow frosting
   To make the marshmallow frosting, fill a medium saucepan with a few inches of water and pop on a medium heat. In a small heatproof bowl, add eggs whites, sugar and cream of tartar. Whisk together.
6. Place the bowl over the saucepan, ensuring the bottom of the bowl does not touch the water below. As the egg whites heat, whisk gently by hand the entire time. Heat the egg whites to 71 C / 160 F which you can test by sticking a candy thermometer – should be around 5-6 minutes or so. By this stage, your sugar should have dissolved. 
7. Remove the bowl from the saucepan and beat using an electric mixer on medium-high speed for approximately 5-6 minutes or until the mixture is fluffy, white and voluminous. Add the vanilla and beat for 30 seconds or so. The marshmallow fluff should no longer be warm.
8. Transfer frosting to a piping bag fitted with a large round or star shaped tip. Pipe tall swirls onto each cupcake. Pop the cupcakes into the freezer for at least 30 minutes for the frosting to firm up.
9. Chocolate dip
   Melt chocolate in the microwave, stirring every 20 seconds or so. Add oil and stir until smooth. Place chocolate in a deep and high sided container. Make sure it’s not hot to the touch – if it is, let it cool slightly before dipping otherwise it will melt the marshmallow frosting.
10. Gently dip each cupcake upside down right into the chocolate, let the chocolate drip off gently and then place the right side up onto a wire rack. Continue to dip all the cupcakes and then place then in the fridge for 30 minutes or so for the chocolate to set.