In a microwave-safe mug, add all-purpose flour, cocoa powder and baking powder. Using a fork, combine everything together.
Then add brown sugar, milk and oil. Give it a good mix. And make sure there are no lumps.
Then microwave it for 1 minute. Take it out and check the texture of the cake. If it feels fluffy or springy to the touch. Then it’s done!
If not, then microwave it in 10-second intervals until fully baked. But don’t overdo it. As it might become too dry or burn.
I have a 900W microwave, and it took 1 minute and 40 seconds to bake this mug cake.
Take it out of the microwave. Let it cool down a little. Then it is ready to serve!