She's a cat = use cat flap as access point.
NOT the bathroom window. Which isn't always open. So she sits on the roof outside and miaows till we open the window.
There is a CAT FLAP!
I put her in the room (utility) where the cat flap is, left some treats on both sides of the flap and shut the door. When I opened the door later, she scarpered having eaten the treats on this side of the flap but not the other side 