Here's another version of the mug cake I just came across.
Mix together any flavor regular cake mix with a box of Angel Food Cake Mix.
I put them both in a large bowl and mixed them together with a whisk.
In a microwave proof mug.
3 Tablespoons of the cake mixture
2 Tablespoons of water Mix well
1 minute in the microwave
This didn't have enough chocolate flavor for me so I added 1 Tablespoon of Dark Chocolate Chips. These are a bit larger than regular chips so they went to the bottom so when I turned it out of the mug it was like chocolate frosting on top! Finely chopped-up chips gave it a more "chocolately" taste.
Now if you want to play around more with this and do a "trial" - you could just take 1 1/2 Tablespoons from a cake mix and 1 1/2 Tablespoons from an Angel Food Cake mixed with the 2 Tablespoons of water. I wouldn't think that this small amount removed would make a difference should you want to go on and make the whole cake mix.
Next "trial" for me - Orange/Angel Food Cake mixes with chocolate chips!
I tried the Orange/Angel Food with mini chocolate chips - Yummy!
If you are finding your cake is too spongy/rubbery add more water. I've found you can use heaping tablespoons of the mix, just be sure to add more water.
Note: Just remember this is NOT for someone with an egg allergy because of the Angel Food Cake Mix.