Expresso Cake in a Mug

My 12 year old great-niece has been staying with me while I'm out of work when both her parents are at work and she loves to cook with me. She helped me make these today and we both loved them. They're easy and fun. You bake individual servings in coffee mugs. When she stirred in the first three ingredients, instant coffee, mini chocolate chips and hot water, she said this smells like coffee and I don't like coffee, but it smells good. Then when we came to the fat free sour cream she said oh no I hate sour cream. I assured her she wouldn't be able to taste it in the cake. Once they came out of the microwave we could hardly wait for them to cool enough to eat. We ate them warm and they were moist and delicious. I was afraid it would bake up over the cup so I used a rather large mug. Next time I will use a smaller one so it will be prettier in the cup.