It was leftover pizza from last night. Katie put the pizza in the oven to keep it away from the dog. And since we had two pieces left, after I got pizza I put it back in there. We both forgot about it and went to bed. Mistakes on our part. Our son also knows to check the oven before turning it on. Mistakes all around. I quizzed the kids on what they would have done if I wasn't there. A nice lesson. All it cost was a house filled with smoke.