Preheat oven to 180°C and lightly grease a 12.5cm/5" cast iron skillet with some butter or non-stick spray.
Combine the peanut butter, Nutella and sugar in a small bowl and mix until thoroughly combined.
Add in the egg white and keep stirring until integrated.
Finally add in the baking soda and choc chips, and stir until just combined (don't overwork the mixture or it can become tough).
Press the mixture evenly into the skillet and bake for 13-15 minutes, until the cookie is golden brown.
Drizzle the top with melted chocolate and enjoy!
