In a microwave-safe mug, combine the flour, sugar, cocoa powder, baking powder, and salt. Stir until well mixed.
Add the milk, vegetable oil, and vanilla extract to the dry ingredients. Mix thoroughly until you achieve a smooth batter.
Gently fold in the chocolate chips, ensuring they are evenly distributed throughout the batter.
Microwave the mug on high for about 40-60 seconds. The cake should rise and look set on the edges while still slightly gooey in the center. Be careful not to overcook!
Let the mug cake cool for a minute before digging in to enjoy the molten center.
Notes
Serve hot and consider adding ice cream or whipped cream for an extra treat.