Begin by taking a microwave-safe mug (approximately 12 oz in capacity) and add the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking powder, and salt. Stir the dry ingredients thoroughly until everything is well combined and there are no lumps remaining.
Next, pour in the milk, vegetable oil, and vanilla extract into the dry mixture. Use a small whisk or fork to mix until you achieve a smooth and consistent batter that is free of clumps.
Gently fold in the semi-sweet and white chocolate chips, ensuring they are evenly dispersed throughout the batter for an explosion of chocolate flavor in every bite.
Place the mug in the microwave and cook on high for 1 minute and 30 seconds. Keep a close watch on the cake as cooking times may vary depending on your microwave's wattage. If the cake has not fully risen or is still gooey in the center, continue cooking in 10-15 second increments until it is set and a toothpick inserted into the center comes out clean.
Carefully take the mug out of the microwave (it will be very hot!), and allow the cake to cool for about one to two minutes.
For an extra luxurious touch, consider topping your cake with a dollop of whipped cream or a scoop of ice cream before digging in to savor this delightful treat straight from the mug!
Notes
For an extra luxurious touch, top with whipped cream or ice cream.