Add all ingredients into a large microwave-safe mug. Mix with a small whisk until batter is completely smooth.
Cook cake at full power in the microwave for about 1 minute or until cake is done. I used an 1100 watt microwave. You may need to adjust cooking time depending on your microwave wattage.
Let cake cool a few minutes. If desired, you can plate in a smaller mug. Top with toppings of your choice. The cake is best eaten soon after it is cooked.
Notes
You can use all purpose flour but your cake won't be quite as light in texture. I normally don't use cake flour for my mug cakes, but because this cake is just vanilla cake with no other mix-ins, I wanted to create something lighter.
Vanilla bean paste is used because it adds more natural vanilla flavor to the cake and specks of vanilla bean too.
You can substitute fat free milk with other milks or milk substitutes.
I recommend making the cake in a large mug and then replating in a smaller mug if desired. It is easier to mix the ingredients in a large mug and it will ensure you cake has enough room to rise.
Since this cake is supposed to be a single serving, it is only the size of an unfrosted cupcake.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.