Prepare Your Mug: Use a microwave-safe mug that holds at least 12 ounces to prevent overflow.
Combine Ingredients: Add the self-rising flour, milk, and sugar to the mug. Stir until just combined, making sure there are no lumps. Avoid overmixing to keep the cake light and fluffy.
Microwave the Mug Cake: Place the mug in the microwave and cook on high for 60 seconds. Check doneness—if the center is still wet, continue microwaving in 10-second intervals until the cake is cooked through.
Cool Slightly: Let the mug cake cool for 1-2 minutes before enjoying—it will be very hot straight out of the microwave.
Add Toppings (Optional): Enhance your mug cake with whipped cream, chocolate sauce, fresh fruit, or a sprinkle of powdered sugar.