Take a powdered cake mix (ideally one that has "pudding in the mix:) and a powdered pudding mix. Combine the powders in a big ziplock and shake to combine.
Mix 1/2 cup of the powder with 1 egg, 1/4 cup water and 1-2 tablespoons oil in a microwave safe dish. A large coffee cup or small bowl works great. Microwave on high for 70 seconds, and turn over onto a plate to eat.
Cake for 1 to 2 people. No leftovers to gorge on at midnight. Unless you make more. Label the ziplock with the recipe and keep for the days when you're desperate for cake. Or when you're at the office.