To start, preheat the oven to gas mark 4/350oF/180oC and line a 12-count muffin tin with 12 muffin cases.
To a large bowl, add the flour, cocoa powder, bicarbonate soda, salt and chocolate chips. Whisk them together and set aside.
To another bowl, mix together the sugar and oil. Then mix in the eggs, vanilla extract, sour cream and milk.
Pour the dry ingredients into the wet ingredients and mix until fully combined. Remember to stop mixing as soon as possible so as soon as you cannot see any white flour.
Spoon the batter into the muffin cases and bake for 20– 22 minutes or until fully baked throughout.
Remove from the oven and allow to cool for 15 minutes then place the muffins on a wire rack to completely cool.