Start by taking your favorite microwave-safe mug. Add in the flour, baking powder, sugar, and salt. Whisk these ingredients together using a fork. This helps ensure you don’t have any lumps while cooking.

Next, make a small well in the center of the dry mix. Pour in the Nutella, vegetable oil, milk, and vanilla extract. Using that same fork (or a spoon, if you prefer), combine the wet and dry ingredients until you reach a smooth batter. Don’t worry about overmixing; it should only take a few seconds to incorporate them well.

Pop your mug into the microwave and cook for about 40 to 60 seconds. Cooking time can vary, depending on your microwave's wattage, so be sure to watch it closely. You want the cake to be set but slightly gooey in the middle. The perfect balance of light and decadent!

Take your mug out of the microwave (it will be hot!), and let it cool for a minute. This allows the cake to firm up slightly. Then, dig in! Feel free to add a dollop of whipped cream on top or even a sprinkle of chopped hazelnuts for a finishing touch.