Quick Coffee Cake in a Cup

My daughter is a Tumblr freak. She is as into that as I am into Pinterest! Or almost that much at least. Anyway... the other day she asked me if she could make something that she saw on there. I blindly said, "yeah, sure. Just clean up after yourself." A few minutes later I smell this delicious aroma wafting through my house. It smelled like freshly baked cinnamon rolls- all gooey and sweet and cinnamony. I was intrigued!
"What the heck IS that FABULOUS smell?!" "Coffee cake in a cup," is what she said. "Gimme some!!," is what I said back. Oh. My. Goodness! I was instantly a fan. You guys have got to try this when you need something sweet and you need it NOW.

Coffee Cake in a Cup for Two

2 Tbsp softened butter
4 Tbsp sugar
1 egg

4 Tbsp sour cream
1/8 tsp vanilla
1/2 cup flour
1/4 tsp baking powder

Crumb Topping:
2 Tbsp softened butter
4 Tbsp flour
2 Tbsp brown sugar
1 tsp cinnamon

In a small bowl, cream butter and sugar with a spoon or fork (mixer is not required.) Add egg, sour cream and vanilla and mix until smooth.
Add flour and baking powder, stir until smooth. Split the batter between two coffee mugs. Set aside.
In a separate small bowl, mix butter, brown sugar, flour, and cinnamon until evenly blended. Split in half and place on top of the batter in each mug.
Cook one mug at a time in the microwave. I would start out with one minute and continue by 10 to 15 second increments. (Ours took about 2 minutes total, but we put it in one giant mug instead of two regular ones.)
Be careful because the mug and the cake will be really hot. Enjoy!