In a microwave-safe mug, combine the flour, sugar, cocoa powder, baking powder, and salt.
Mix the dry ingredients thoroughly using a fork.
Add the milk, vegetable oil, and vanilla extract to the dry mixture.
Stir until you achieve a smooth batter.
Ensure there are no dry clumps remaining.
Microwave the mug on high for about 1 minute.
Check for doneness; if it's not set, microwave for an additional 10-15 seconds.
Let the mug cake cool for a minute before eating.
Optionally, drizzle with caramel or chocolate sauce.
Enjoy your delicious mug cake directly from the mug!