Preheat oven to 190 °C fan

Mix dry ingredients

Sift the cocoa powder then add hot milk. Whisk until lump free then add sugar, oil, egg, sour cream and vanilla extract. Whisk until smooth

Pour wet mix into the dry. Stop once it's smooth

Add chocolate chips

Divide the batter

Bake at high temperature for 5 mins. then lower the temperature to 170 °C and continue baking for further 20 mins