1. Add flour, sugar, salt and baking powder to mug. Mix.

2. Add water and oil. Mix. Mixture should be liquid-ish. You may need to adjust liquids. Add banana and peanut butter. Mix.

3. Add vanilla and cinnamon. Mix. Take your mug to a microwave for 3 minutes. The cake will have a pale color once the 3 minutes are over. Fact: don't get fooled if you think that the cake is not ready yet, it is ready!

Source of recipe: I randomly put stuff inside a mug and 5 minutes later = Kaboom!'