Begin by selecting a microwave-safe mug. In it, add the all-purpose flour, sugar, baking powder, and pinch of salt. Use a whisk or fork to mix these dry ingredients thoroughly until they are evenly combined.
Next, introduce the wet ingredients: spoon in the creamy peanut butter, pour in the milk, add the vegetable oil, and sprinkle in the vanilla extract. Stir the mixture vigorously until you achieve a smooth and lump-free batter.
For a delightful twist, fold in chocolate chips or crushed nuts at this stage, enhancing both texture and flavor. This step is completely optional but highly recommended for a fun surprise!
Place the mug in the microwave and cook on high for 1 minute and 20 seconds. Be mindful that cooking times may vary slightly depending on the power of your microwave. After the initial cooking time, check your cake; it should feel springy and slightly puffed when touched. If needed, continue microwaving in additional 10-second intervals until fully cooked.
Once done, carefully remove the mug (it will be hot!) and allow it to cool for about a minute. This will help prevent any accidental burns when you dive into your scrumptious mug cake!
Notes
For a vegan option, use plant-based milk and coconut oil.