Begin by selecting a microwave-safe mug. In the mug, combine the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking powder, and salt. Use a small whisk or fork to mix these dry ingredients thoroughly, ensuring there are no clumps.
Next, add the milk, vegetable oil, and vanilla extract to the mug. Stir the mixture until it transforms into a smooth batter with no lumps.
Take your chocolate square or chocolate chips and gently press them into the center of the batter. Ensure they are submerged slightly, as this will create the molten lava effect when cooked.
Place the mug in the microwave and cook on high for 40-60 seconds. Start checking the cake at the 40-second mark. You’re looking for it to be slightly firm around the edges while remaining soft and gooey in the middle. Be cautious not to overcook, as it is the melted chocolate that provides the luxurious 'lava' experience!
After microwaving, carefully remove the mug (it may be hot!) and allow it to cool for about one minute. For an added touch of elegance, sprinkle powdered sugar over the top before serving. Enjoy your decadent treat straight from the mug!
Notes
Be careful not to overcook to maintain the lava effect.