Hey guys,

I am baking a 12x18 sheet cake. Well this is my first time doing such a large sheet cake in my oven...the oven door will not completely close....will the cake still cook properly???

If you pan has four flat lips around the edge, you can use pliers to pry them upwards on one or two of the sides to get your oven door to close the rest of the way.

In some ovens, if you prop your pan up on another upside down pan, it will raise it enough to clear the oven door because it will be aligned with the recessed window area.

well, the cake might already be baked, but if you need a fast fix I would try to cover the gap with tin foil to keep the heat in and maybe boost the temp about ten degrees.
Next time, when you bake a larger-than-your-oven sized cake, maybe pour the batter into two smaller sized pans that you can piece together on the cake board.
Sounds like it's time for a new oven if a 12" X 18" pan is maxing out your oven!

Yeah, the house that I live in (I'm renting) has an old oven that is built into the wall and it is rather small. Anyway, the cake did bake fine. I thought it was gonna be all kinds of problems but it was not.