Step 1

Preheat oven to 190 degrees Celsius for 10 mins.

Step 2

Butter your mug thoroughly and be careful not to miss a spot! Pour in sugar and rotate cup to entirely coat the insides of the mug. Put aside.

Step 3

Use hands to combine salt, butter and flour together until no more flour can be seen.

Step 4

Put 20g sugar and milk into a pan and bring it up to a tiny boil. Throw in the flour/salt/butter mixture and whisk till smooth. Break dark chocolate slab into pieces and throw in. Whisk again till smooth.

Step 5

Whisk egg whites till foamy. Throw in remaining (10g sugar) and whisk again till white stiff peaks form. Careful not to over-whisk!

Step 6

Carefully fold in egg whites into the chocolatey mixture that's been sitting on your stove. Mix till smooth. Pour final mixture into the waiting mug. Wipe away any residual mixture on sides of mug that will give trouble to the little soufflé that's trying to rise in the oven.

Step 7

Put in preheated oven for 17 mins. Dust with icing sugar and serve immediately. It'll be nice with a cup of tea or vanilla ice-cream (which I don't have at the moment