Tales of the Domestically Challenged: Cleaning the Oven

About a month ago our oven began to emit gentle puffs of smoke when being preheated. The sort of

Sometimes you stare into the abyss. Sometimes the abyss needs cleaning.

puffing you would pleasantly associate with your grandfather's pipe if you had a grandfather who possessed such a hobby.

I did not have such a grandfather so I immediately thought: "That can't be good." I wondered if my oven was now really, really, really a fire hazard.  I muttered, "What could be burning in there?"  I stood back and frowned but I did not turn my back to the oven because ovens are sneaky bastards just like all household appliances. 

The wheels in my head turned slowly until they groaned to a stop many months ago when my friend Amy came over and used our oven to make a snack. She opened the oven and exclaimed: "Woah! You need to clean your oven!"