You can get magnetic cat doors which only unlock if the cat is wearing a special collar to let them in. Otherwise move the food out of the laundry.
This would be my suggestion. Also, if you are happy to have her "locked in" you can make it so she can come in but not go back out?

funny story (maybe not for some) I worked for a vet who had a similar problem with a tom cat coming into her home & spraying everywhere. She invested in the magnetic cat flap thingy & also set it up to the cats come get in but not out. She came home to find the visiting Tom cat locked in her house, so she caught him. knocked him out, castrated him & let him out in the morning. Pretty sure he wasn't a problem after that.