Add 4 tbsp self-raising flour, 4 tbsp caster sugar and 2 tbsp cocoa powder to the largest mug you have (to stop it overflowing in the microwave) and mix.

Add 1 medium egg and mix in as much as you can, but don't worry if there's still dry mix left.

Add the 3 tbsp milk, 3 tbsp vegetable or sunflower oil and a few drops of vanilla essence and mix until smooth, before adding 2 tbsp chocolate chips, nuts, or raisins, if using, and mix again.

Centre your mug in the middle of the microwave oven and cook on High for 1½ -2 mins, or until it has stopped rising and is firm to the touch.