There's a really cute chick working at a drive thru I go to frequently. How do I go about asking her out without bothering her at work? I've been seeing her fairly regularly, at least once a week. Wat do?

There's a really cute chick working at a fast food drive thru that I go to frequently. How do I go about asking her out without bothering her while she's working? How can I tell if she thinks I'm cute or not?