Offer her a shower and say "goodnight"

"So I guess you have to go. Would you like to use my shower to clean up before you do?

"Um, yeah, that might be nice" she says as she composes herself. You show her to the bathroom and pull out a spare towel for her. You go back out to the living room while she showers, and about 10 minutes later she comes out fully dressed again.

"Thanks for being so generous with the cookies," she says as she gives you a peck on the cheek. Claire opens the door and waves as she heads out of your apartment.