Steps
In a microwave-safe mug, combine the flour, sugar, cocoa powder, baking powder, and salt. Stir until mixed well.
Add the milk, vegetable oil, and vanilla extract. Mix until smooth and combined.
Fold in the chocolate chips if using.
Microwave on high for about 1 minute and 30 seconds, or until the cake has risen and is set in the middle.
Let it cool slightly before enjoying straight from the mug!