Place all the grated chocolate and dry ingredients in bowl and combine well.
Add the egg, coconut oil and coffee.
Mix until combined.
Divide the mixture between 2 mugs.
The mug cake will raise when cooked so use a large enough mug or cup (fill it up to no more than half).
Microwave on high for 70-90 seconds, until cooked through.
Preheat the oven to 175 °C/ 350 °F and cook for about 12-15 minutes or until cooked in the centre.
You can optionally top the mug cake with whipped cream or creamed coconut milk and or creme fraiche.