My electric oven has a timer, but not an automatic shutoff.

So all the timer does, is beep.

Seems to me, if I bake a cake for 350 degrees and one hour,
I'd want, for safety reasons, the oven to shut off at some
point too far past that set hour.

But, mine just runs forever.

Do that make an oven that shuts off with a timer?
Can it be retrofitted to an existing oven?