Baking Disaster

So today I had my first baking disaster. I made brownies and I saw that they weren't quite as thick as the photo looked that I was using. Instead of looking like this when they were done:

They turned out like this:

And the oven looks like this:

 This made a huge cloud in the apartment. I turned on both bathroom fans, the 3 ceiling fans, and the above oven fan and opened the porch door. I still don't know how it didn't set off the smoke alarms though. It was crazy! I havn't tried what is left of them yet...I'm sort of angry with them at the moment...grrrr. I have always been able to follow recipes and have never ever had anything close to this happen before. Sigh....