Try this quick and easy way to make brownies with hardly any washing up!
Spoon the flour, sugar, cacao powder, salt and cinnamon into a microwavable mug. Combine by mixing with a fork. Add the water, butter and vanilla and stir until combined.
Place in the microwave for 1 minute and 40 seconds or until cooked through. You may need to adjust the time depending on how powerful your microwave is.
Serve with ice cream!