What a great recipe!
I've made the cake many times now after finding this topic and I thought I might share my tweaks with y'all. There's one extra step and a few more ingredients and it's basically put together in reverse order, but it really pays off.
The texture is nicer if it's cooked in a bowl but the mug is so cute.
Melt 3 T butter, add 3 T milk, a tiny bit of vanilla, and an egg. Beat it all up. Add 4 T flour, 5 1/2 T sugar (just eye it
), 2 scant T cocoa powder, a small pinch of baking powder, and a pinch of salt. Microwave for 3 minutes.
Notes on my changes: Butter is generally more flavorful than oil, so that had to be in. Vanilla helps flavoring a lot too. The first time I made the cake it was pretty bitter, so I increased the sugar by a tablespoon. It was still too bitter, so I tried 6 tablespoons, which was too sweet, so the happy medium was 5 1/2. Some people on this thread suggested the baking powder, which definitely made it better. Then I gave the recipe to a friend, and the credit for the salt goes to her- it does help.
The bottom sometimes gets kind of soggy and weird, but if you turn it out right away and sprinkle lots of powdered sugar on it you'd never know.