You can lightly grease the inside of the mug with a bit of butter or oil to prevent sticking, but it's not necessary.

In the mug, whisk together the all-purpose flour, granulated sugar, and baking powder until well combined. This will ensure that your mug cake rises properly and has a nice texture.

Pour in the milk, melted butter or oil, and vanilla extract into the mug with the dry ingredients. Stir everything together until you have a smooth batter. If you're adding sprinkles, gently fold them into the batter now.

Place the mug in the microwave and cook on high for about 1 to 2 minutes, depending on the wattage of your microwave. Start with 1 minute and check the cake's doneness by inserting a toothpick into the center. If it comes out clean, your mug cake is ready. If not, continue microwaving in 15 to 30-second intervals until done. Remember, cooking time will vary depending on your microwave wattage.

Carefully remove the mug from the microwave (it will be hot!) and let it cool for a minute or two. You can enjoy the mug cake directly from the mug or transfer it to a plate. If desired, you can add a dollop of whipped cream, a scoop of vanilla ice cream, or extra sprinkles on top for decoration.

Grab a spoon and dig into your warm and delicious vanilla mug cake! Enjoy it as a quick and satisfying dessert anytime you need a sweet treat fix.