<human>: Can you condense the text into three sentences or less?

This is the second time I've started a fire this way unfortunately... my mother in law made this awesomely huge cakes for my son's birthday party. We found it much easier to keep it fresh a little longer if we leave it in the oven (off) instead of wrapping it in foil. 

Well tonight I needed to cook something, and forgot about the cake in the oven (and foil, and paper plates) and didn't realize until I started smelling S'mores. (Awesomest house fire ever)

Anyway, the icing melted all over the heating element and was flaming up good. It started to spread so I gave it a quick blast with a mini kitchen sized fire extinguisher.

What do I need to do (self clean only? scrub out the residue?) before its safe to use the oven again? I'm worried about cooking the left over extinguisher residue into my food.
<bot>: used a fire extinguisher in my oven, what's the best way to clean it to make it safe to cook with again