I found the recipe on Babble.http://blogs.babble.com/family-kitchen/2011/09/13/two-minute-mug-brownie/
1/4 cup flour
1/4 cup brown sugar
2T unsweetened cocoa powder
Pinch of salt
2T milk, water or coffee
In heatproof mug or ramekin stir dry ingredients together until no lumps. Stir in liquids until you have a paste.
Microwave 1 minute checking after 30 seconds. It depends on your microwave strength for time. Brownie should be spongy on top but gooey inside.
I think I cooked mine a few second too long because I didn't have gooey. This is super rich and I could only eat half of it. I will definitely do this again just with a different recipe. Super easy.
Dry ingredients in my cute Beagle mug
The finished product.