Steps
In a microwave-safe mug, mix the flour, sugar, cocoa powder, baking powder, and salt until well combined.
Add in the milk, vegetable oil, and vanilla extract. Stir until smooth and there are no lumps.
Fold in the chocolate chips, if using.
Microwave on high for 1 minute and 30 seconds, or until the cake has risen and is set in the middle.
Let it cool for a minute before enjoying your warm chocolate mug cake!