What settings does your oven offer? Usually an oven should have proper venting of excessive moisture. Are you maybe using a special "steaming" setting instead of regular heating? If it's a regular setting that you're using, your oven might have a technical problem with ventilation that a service mechanic might be able to fix.
As a meantime band-aid fix, you might want to quickly open your oven door ever so often to let out excessive steam. If this does nothing to reduce the amount of steam, it might indeed be a steaming setting that somehow traps or even injects moisture into your oven chamber.