In a microwave-safe mug, combine the all-purpose flour, granulated sugar, and baking powder. Mix well to ensure there are no lumps.
Add the unsweetened almond milk, vegetable oil, and vanilla extract to the dry ingredients. Stir until the mixture is smooth and well combined.
If desired, fold in vegan chocolate chips or sprinkles for an extra touch of sweetness and fun.
Microwave the mug on high for about 1 minute and 30 seconds. Cooking times may vary depending on your microwave's wattage, so keep an eye on the cake as it cooks.
Once the cake has risen and is set in the middle, carefully remove the mug from the microwave. Allow it to cool for a minute before indulging in your delicious vegan vanilla mug cake.