The only difference between your recipe and mine is that I don't eat dairy due to casein intolerance - so I used plain, unsweetened almond milk. Somehow, it turned out apocalyptic. Maybe it's because I'm at sea level. Maybe it's because of the barometric pressure being highly unstable in my city. Maybe it's just an ancient god of baking looking down upon me. But it never rose properly. Despite following the recipe to the letter, the second I took it out, it deflated and began to sizzle. My brother walked in and asked what I set on fire. Nothing - though I then set the smoke alarm off by walking to put it to cool and maybe salvage it with some dairy-free chocolate chips. Everything I used was fresh and measured well. My mug was made for cakes, soups, and soufflés. There should have been zero problem. But no, it's a congealed, burnt mess that is weirdly rising AFTER the fact. My baking soda is just a normal store brand we've used for years. No fancy stuff. So it's not that. My microwave is a normal Sylvania model that has adjustable power. I did it at 1200W, and then tried a new cake at 1000W just to be safe. It exploded. It freakin' exploded. I cannot endorse a recipe that causes my microwave to get burnt cocoa stuck in its vents forever. Sorry.
