Man, you need to decsipline little brats like that. After he burned his finger by DIRECTLY disobeying you, you should have taken the pizza out of the oven and dumped it on his head. You then should have dumped soda on him. Then pick him up and put him head first into the trashcan, so the ants will eat the food and soda off of him.
I garuntee, he will never go near an oven again, and it would be damn funny as well.