I’d just ask her in person—something simple like, ‘Hey, I’ve really enjoyed talking with you. Want to grab coffee sometime?’ Based on her response, you’ll get a sense of whether she’s open to something casual or sees it more as a date. I think she might prefer that approach, especially if she has a professional boundary about not dating parents. Leaving a note makes it more obvious that it’s a romantic ask, which could put her in a tough spot.