Step 1

In an 8 oz microwave-safe mug, add cocoa, flour and sugar. Whisk together with a mini whisk.

Step 2

Add in oil and water. Whisk briskly until batter is smooth, making sure to break up any cocoa or flour lumps.

Step 3

Add half the chocolate to the mug and briefly stir into batter. Sprinkle remaining chocolate on top of the batter.

Step 4

Cook cake for about 40 seconds at full power. (I used a 1000 watt microwave. You may need to adjust time and/or power if you are using a different wattage.) Top of brownie should no longer be wet but may still be a little moist. Allow brownie to cool a few minutes and then eat the brownie while warm.