My mum always uses caustic soda ...but be careful as it burns so wear rubber gloves..personally i use Mr Muscle oven cleaner but again be carefull as the can states not to inhale any of the fumes, just take a deep breath then spray liberally onto the baked-on parts to be cleaned and leave the room ..closing the door for a good twenty minutes before entering the kitchen again. The ammount of time needed depends on how baked-on the baked-on parts are so test by wiping a small part with a damp sponge and its always best to wear rubber gloves.